diff --git a/.gitignore b/.gitignore
index 6bd2bb3533..a56c40a4d1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -128,6 +128,7 @@ linux-build
 win32-build
 test/config.ini
 test/cache/*
+test/.mypy_cache/
 
 !src/leveldb*/Makefile
 
diff --git a/ci/lint/04_install.sh b/ci/lint/04_install.sh
index e7758a8c57..40fe6c3fd3 100755
--- a/ci/lint/04_install.sh
+++ b/ci/lint/04_install.sh
@@ -14,6 +14,7 @@ travis_retry pip3 install codespell==1.17.1
 travis_retry pip3 install flake8==3.8.3
 travis_retry pip3 install vulture==2.3
 travis_retry pip3 install yq
+travis_retry pip3 install mypy==0.700
 
 SHELLCHECK_VERSION=v0.6.0
 curl -s "https://storage.googleapis.com/shellcheck/shellcheck-${SHELLCHECK_VERSION}.linux.x86_64.tar.xz" | tar --xz -xf - --directory /tmp/
diff --git a/test/functional/README.md b/test/functional/README.md
index 11485ed03a..efb69a5234 100644
--- a/test/functional/README.md
+++ b/test/functional/README.md
@@ -26,10 +26,12 @@ don't have test cases for.
   The Travis linter also checks this, but [possibly not in all cases](https://github.com/bitcoin/bitcoin/pull/14884#discussion_r239585126).
 - See [the python lint script](/test/lint/lint-python.sh) that checks for violations that
   could lead to bugs and issues in the test code.
+- Use [type hints](https://docs.python.org/3/library/typing.html) in your code to improve code readability
+  and to detect possible bugs earlier.
 - Avoid wildcard imports
 - Use a module-level docstring to describe what the test is testing, and how it
   is testing it.
-- When subclassing the BitcoinTestFramwork, place overrides for the
+- When subclassing the BitcoinTestFramework, place overrides for the
   `set_test_params()`, `add_options()` and `setup_xxxx()` methods at the top of
   the subclass, then locally-defined helper methods, then the `run_test()` method.
 - Use `f'{x}'` for string formatting in preference to `'{}'.format(x)` or `'%s' % x`.
@@ -45,7 +47,7 @@ don't have test cases for.
     - `rpc` for tests for individual RPC methods or features, eg `rpc_listtransactions.py`
     - `tool` for tests for tools, eg `tool_wallet.py`
     - `wallet` for tests for wallet features, eg `wallet_keypool.py`
-- use an underscore to separate words
+- Use an underscore to separate words
     - exception: for tests for specific RPCs or command line options which don't include underscores, name the test after the exact RPC or argument name, eg `rpc_decodescript.py`, not `rpc_decode_script.py`
 - Don't use the redundant word `test` in the name, eg `interface_zmq.py`, not `interface_zmq_test.py`
 
diff --git a/test/functional/data/invalid_txs.py b/test/functional/data/invalid_txs.py
index 946afcc265..95114fdf12 100644
--- a/test/functional/data/invalid_txs.py
+++ b/test/functional/data/invalid_txs.py
@@ -21,6 +21,7 @@ Invalid tx cases not covered here can be found by running:
 """
 import abc
 
+from typing import Optional
 from test_framework.messages import (
     COutPoint,
     CTransaction,
@@ -39,7 +40,7 @@ class BadTxTemplate:
     __metaclass__ = abc.ABCMeta
 
     # The expected error code given by bitcoind upon submission of the tx.
-    reject_reason = ""
+    reject_reason = ""  # type: Optional[str]
 
     # Only specified if it differs from mempool acceptance error.
     block_reject_reason = ""
diff --git a/test/functional/test_framework/script.py b/test/functional/test_framework/script.py
index 6ec17a11f0..51da54081c 100644
--- a/test/functional/test_framework/script.py
+++ b/test/functional/test_framework/script.py
@@ -8,6 +8,7 @@ This file is modified from python-bitcoinlib.
 """
 import struct
 import unittest
+from typing import List, Dict
 
 from .messages import (
     CTransaction,
@@ -19,7 +20,7 @@ from .messages import (
 from .ripemd160 import ripemd160
 
 MAX_SCRIPT_ELEMENT_SIZE = 520
-OPCODE_NAMES = {}
+OPCODE_NAMES = {}  # type: Dict[CScriptOp, str]
 
 def hash160(s):
     return ripemd160(sha256(s))
@@ -35,7 +36,7 @@ def bn2vch(v):
     # Serialize to bytes
     return encoded_v.to_bytes(n_bytes, 'little')
 
-_opcode_instances = []
+_opcode_instances = []  # type: List[CScriptOp]
 class CScriptOp(int):
     """A single script opcode"""
     __slots__ = ()
diff --git a/test/functional/test_framework/test_framework.py b/test/functional/test_framework/test_framework.py
index d094fe2d1f..53d1ac8f74 100755
--- a/test/functional/test_framework/test_framework.py
+++ b/test/functional/test_framework/test_framework.py
@@ -112,6 +112,9 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
 
     This class also contains various public and private helper methods."""
 
+    chain = None  # type: str
+    setup_clean_chain = None  # type: bool
+
     def __init__(self):
         """Sets test framework defaults. Do not override this method. Instead, override the set_test_params() method"""
         self.chain: str = 'regtest'
@@ -460,7 +463,7 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
 
     # Public helper methods. These can be accessed by the subclass test scripts.
 
-    def add_nodes(self, num_nodes, extra_args=None, *, rpchost=None, binary=None, binary_cli=None, versions=None):
+    def add_nodes(self, num_nodes: int, extra_args=None, *, rpchost=None, binary=None, binary_cli=None, versions=None):
         """Instantiate TestNode objects.
 
         Should only be called once after the nodes have been specified in
diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
index 73623c9d50..97cca9c626 100755
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -43,7 +43,7 @@ except UnicodeDecodeError:
 if os.name != 'nt' or sys.getwindowsversion() >= (10, 0, 14393):
     if os.name == 'nt':
         import ctypes
-        kernel32 = ctypes.windll.kernel32
+        kernel32 = ctypes.windll.kernel32  # type: ignore
         ENABLE_VIRTUAL_TERMINAL_PROCESSING = 4
         STD_OUTPUT_HANDLE = -11
         STD_ERROR_HANDLE = -12
diff --git a/test/lint/lint-python.sh b/test/lint/lint-python.sh
index 8112b2b078..958e1df47d 100755
--- a/test/lint/lint-python.sh
+++ b/test/lint/lint-python.sh
@@ -7,6 +7,7 @@
 # Check for specified flake8 warnings in python files.
 
 export LC_ALL=C
+export MYPY_CACHE_DIR="${BASE_ROOT_DIR}/test/.mypy_cache"
 
 enabled=(
     E101 # indentation contains mixed spaces and tabs
@@ -103,3 +104,5 @@ PYTHONWARNINGS="ignore" $FLAKECMD --ignore=B,C,E,F,I,N,W --select=$(IFS=","; ech
         echo "$@"
     fi
 )
+
+mypy --ignore-missing-imports $(git ls-files "test/functional/*.py")
\ No newline at end of file