diff --git a/README.rst b/README.rst
index 3ef1acd..4396ee4 100644
--- a/README.rst
+++ b/README.rst
@@ -44,6 +44,9 @@ expressions like the following:
 - ``5hr34m56s``
 - ``5 hours, 34 minutes, 56 seconds``
 - ``5 hrs, 34 mins, 56 secs``
+- ``250ms``
+- ``1 second, 250 milliseconds``
+- ``1m 500ms``
 - ``2 days, 5 hours, 34 minutes, 56 seconds``
 - ``1.2 m``
 - ``1.2 min``
diff --git a/pytimeparse/tests/testtimeparse.py b/pytimeparse/tests/testtimeparse.py
index d9e15b3..a2e20ed 100644
--- a/pytimeparse/tests/testtimeparse.py
+++ b/pytimeparse/tests/testtimeparse.py
@@ -133,6 +133,37 @@ def test_fractional_units_exact_integer_results(self):
                     timeparse.timeparse(prefix + text), sign * expected, prefix + text
                 )
 
+    def test_milliseconds(self):
+        for unit in ('ms', 'msec', 'msecs', 'millis', 'millisecond',
+                     'milliseconds', 'MS'):
+            for prefix, sign in [('', 1), ('+', 1), ('-', -1)]:
+                self.assertEqual(timeparse.timeparse(prefix + '250 ' + unit),
+                                 sign * 0.25)
+
+    def test_milliseconds_with_other_units(self):
+        cases = [('1s250ms', 1.25), ('1m 500ms', 60.5),
+                 ('1h, 2m, 3s, 500ms', 3723.5),
+                 ('1.5s 250ms', 1.75), ('0.5m 250ms', 30.25),
+                 ('0.5ms', 0.0005), ('9ms', 0.009),
+                 ('4.1m500ms', 246.5), ('2.3d1ms', 198720.001)]
+        for text, expected in cases:
+            for prefix, sign in [('', 1), ('+', 1), ('-', -1)]:
+                self.assertEqual(timeparse.timeparse(prefix + text),
+                                       sign * expected)
+
+    def test_whole_seconds_from_milliseconds(self):
+        for text, expected in [('0ms', 0), ('1000ms', 1),
+                               ('1s1000ms', 2), ('1.5s500ms', 2)]:
+            result = timeparse.timeparse(text)
+            self.assertEqual(result, expected)
+            self.assertIsInstance(result, int)
+
+    def test_invalid_milliseconds(self):
+        for text in ('ms', '.ms', '1.2.3ms', '1ms1s',
+                     '1s-250ms', '1ms1ms', '1 microsecond',
+                     '1s,', ',250ms'):
+            self.assertIsNone(timeparse.timeparse(text), text)
+
     def test_timeparse_1(self):
         """timeparse test case 1."""
         self.assertEqual(timeparse.timeparse("32m"), 1920)
diff --git a/pytimeparse/timeparse.py b/pytimeparse/timeparse.py
index 93e8001..84a77c0 100644
--- a/pytimeparse/timeparse.py
+++ b/pytimeparse/timeparse.py
@@ -42,6 +42,7 @@
 HOURS = r"(?P<hours>[\d.]+)\s*(?:h|hrs?|hours?)"
 MINS = r"(?P<mins>[\d.]+)\s*(?:m|(mins?)|(minutes?))"
 SECS = r"(?P<secs>[\d.]+)\s*(?:s|secs?|seconds?)"
+MILLIS = r"(?P<millis>[\d.]+)\s*(?:ms|msecs?|millis|milliseconds?)"
 SEPARATORS = r"[,/]"
 SECCLOCK = r":(?P<secs>\d{2}(?:\.\d+)?)"
 MINCLOCK = r"(?P<mins>\d{1,2}):(?P<secs>\d{2}(?:\.\d+)?)"
@@ -54,7 +55,7 @@
 OPTSEP = lambda x: r"(?:{x}\s*(?:{SEPARATORS}\s*)?)?".format(x=x, SEPARATORS=SEPARATORS)
 
 TIMEFORMATS = [
-    r"{WEEKS}\s*{DAYS}\s*{HOURS}\s*{MINS}\s*{SECS}".format(
+    r"{WEEKS}\s*{DAYS}\s*{HOURS}\s*{MINS}\s*{SECS}\s*{MILLIS}".format(
         # YEARS=OPTSEP(YEARS),
         # MONTHS=OPTSEP(MONTHS),
         WEEKS=OPTSEP(WEEKS),
@@ -62,6 +63,8 @@
         HOURS=OPTSEP(HOURS),
         MINS=OPTSEP(MINS),
         SECS=OPT(SECS),
+        # A seconds field may be followed by a separator, but not on its own.
+        MILLIS=OPT(r"(?(secs)[,/]?\s*)" + MILLIS),
     ),
     r"{MINCLOCK}".format(MINCLOCK=MINCLOCK),
     r"{WEEKS}\s*{DAYS}\s*{HOURCLOCK}".format(
@@ -89,6 +92,7 @@
         ("hours", 60 * 60),
         ("mins", 60),
         ("secs", 1),
+        ("millis", Decimal("0.001")),
     ]
 )
 
@@ -173,7 +177,9 @@ def timeparse(sval: str, granularity: str = "seconds") -> Optional[Union[int, fl
                 mdict = _interpret_as_minutes(sval, mdict)
             try:
                 # if all of the fields are integer numbers
-                if all(v.isdigit() for v in list(mdict.values()) if v):
+                if mdict.get("millis") is None and all(
+                    v.isdigit() for v in list(mdict.values()) if v
+                ):
                     return sign * sum(
                         [
                             MULTIPLIERS[k] * int(v, 10)
@@ -182,7 +188,7 @@ def timeparse(sval: str, granularity: str = "seconds") -> Optional[Union[int, fl
                         ]
                     )
                 # if SECS is an integer number
-                elif (
+                elif mdict.get("millis") is None and (
                     "secs" not in mdict
                     or mdict["secs"] is None
                     or mdict["secs"].isdigit()
@@ -203,14 +209,15 @@ def timeparse(sval: str, granularity: str = "seconds") -> Optional[Union[int, fl
                         + (int(mdict["secs"], 10) if mdict["secs"] else 0)
                     )
                 else:
-                    # SECS is a float, we will return a float
-                    return sign * sum(
+                    # Preserve subsecond precision until the final conversion.
+                    result = sign * sum(
                         [
-                            MULTIPLIERS[k] * float(v)
+                            MULTIPLIERS[k] * Decimal(v)
                             for (k, v) in list(mdict.items())
                             if v is not None
                         ]
                     )
+                    return int(result) if result == int(result) else float(result)
             except (ValueError, InvalidOperation):
                 # Malformed number string (e.g. '1.2.3', '.') — skip to
                 # the next time format pattern per documented behavior.