diff --git a/doc/source/whatsnew/v3.0.0.rst b/doc/source/whatsnew/v3.0.0.rst
index cd6977f43d322..133e7149d4546 100644
--- a/doc/source/whatsnew/v3.0.0.rst
+++ b/doc/source/whatsnew/v3.0.0.rst
@@ -182,6 +182,7 @@ Other Deprecations
 - Deprecated :meth:`Timestamp.utcnow`, use ``Timestamp.now("UTC")`` instead (:issue:`56680`)
 - Deprecated allowing non-keyword arguments in :meth:`Series.to_markdown` except ``buf``. (:issue:`57280`)
 - Deprecated allowing non-keyword arguments in :meth:`Series.to_string` except ``buf``. (:issue:`57280`)
+- Deprecated strings ``MIN``, ``MS``, ``US``, and ``NS`` denoting units in :class:`Timedelta` and :func:`to_timedelta` (:issue:`57700`)
 -
 
 .. ---------------------------------------------------------------------------
diff --git a/pandas/_libs/tslibs/dtypes.pyx b/pandas/_libs/tslibs/dtypes.pyx
index c0d1b2e79f587..8f1a845a268ed 100644
--- a/pandas/_libs/tslibs/dtypes.pyx
+++ b/pandas/_libs/tslibs/dtypes.pyx
@@ -401,6 +401,9 @@ cdef dict c_DEPR_ABBREVS = {
     "u": "us",
     "N": "ns",
     "n": "ns",
+    "MIN": "min",
+    "US": "us",
+    "NS": "ns",
 }
 
 
diff --git a/pandas/_libs/tslibs/timedeltas.pyx b/pandas/_libs/tslibs/timedeltas.pyx
index 18ead7d5381df..befab1dfaddf0 100644
--- a/pandas/_libs/tslibs/timedeltas.pyx
+++ b/pandas/_libs/tslibs/timedeltas.pyx
@@ -719,6 +719,14 @@ cpdef inline str parse_timedelta_unit(str unit):
         return "ns"
     elif unit == "M":
         return unit
+    elif unit == "MS":
+        warnings.warn(
+            f"\'{unit}\' is deprecated and will be removed in a future version. "
+            f"Please use \'ms\' instead of \'{unit}\'.",
+            FutureWarning,
+            stacklevel=find_stack_level(),
+        )
+        unit = "ms"
     elif unit in c_DEPR_ABBREVS:
         warnings.warn(
             f"\'{unit}\' is deprecated and will be removed in a "
@@ -1801,6 +1809,11 @@ class Timedelta(_Timedelta):
             Values `H`, `T`, `S`, `L`, `U`, and `N` are deprecated in favour
             of the values `h`, `min`, `s`, `ms`, `us`, and `ns`.
 
+        .. deprecated:: 3.0.0
+
+            Units `MIN`, `MS`, `US`, and `NS` are deprecated in favour
+            of the units `min`, `ms`, `us`, and `ns`.
+
     **kwargs
         Available kwargs: {days, seconds, microseconds,
         milliseconds, minutes, hours, weeks}.
diff --git a/pandas/core/groupby/generic.py b/pandas/core/groupby/generic.py
index a88bd4c42edec..d48592d1a61cb 100644
--- a/pandas/core/groupby/generic.py
+++ b/pandas/core/groupby/generic.py
@@ -20,7 +20,6 @@
     Union,
     cast,
 )
-import warnings
 
 import numpy as np
 
@@ -32,7 +31,6 @@
     Substitution,
     doc,
 )
-from pandas.util._exceptions import find_stack_level
 
 from pandas.core.dtypes.common import (
     ensure_int64,
diff --git a/pandas/tests/indexes/timedeltas/test_timedelta_range.py b/pandas/tests/indexes/timedeltas/test_timedelta_range.py
index f22bdb7a90516..6638c047154c8 100644
--- a/pandas/tests/indexes/timedeltas/test_timedelta_range.py
+++ b/pandas/tests/indexes/timedeltas/test_timedelta_range.py
@@ -171,3 +171,23 @@ def test_timedelta_range_deprecated_freq(
             expected_values, dtype="timedelta64[ns]", freq=expected_freq
         )
         tm.assert_index_equal(result, expected)
+
+    @pytest.mark.parametrize(
+        "depr_unit, unit",
+        [
+            ("MIN", "min"),
+            ("MS", "ms"),
+            ("US", "us"),
+            ("NS", "ns"),
+        ],
+    )
+    def test_timedelta_units_MIN_MS_US_NS_deprecated(self, depr_unit, unit):
+        # GH#52536
+        depr_msg = (
+            f"'{depr_unit}' is deprecated and will be removed in a future version."
+        )
+
+        expected = to_timedelta(np.arange(5), unit=unit)
+        with tm.assert_produces_warning(FutureWarning, match=depr_msg):
+            result = to_timedelta(np.arange(5), unit=depr_unit)
+            tm.assert_index_equal(result, expected)
diff --git a/pandas/tests/scalar/timedelta/test_constructors.py b/pandas/tests/scalar/timedelta/test_constructors.py
index e680ca737b546..b383630aeb512 100644
--- a/pandas/tests/scalar/timedelta/test_constructors.py
+++ b/pandas/tests/scalar/timedelta/test_constructors.py
@@ -170,6 +170,24 @@ def test_unit_parser(self, unit, np_unit, wrapper):
             result = Timedelta(f"2{unit}")
             assert result == expected
 
+    @pytest.mark.parametrize(
+        "unit,unit_depr",
+        [
+            ("min", "MIN"),
+            ("ms", "MS"),
+            ("us", "US"),
+            ("ns", "NS"),
+        ],
+    )
+    def test_units_MIN_MS_US_NS_deprecated(self, unit, unit_depr):
+        # GH#52536
+        msg = f"'{unit_depr}' is deprecated and will be removed in a future version."
+
+        expected = Timedelta(1, unit=unit)
+        with tm.assert_produces_warning(FutureWarning, match=msg):
+            result = Timedelta(1, unit=unit_depr)
+        tm.assert_equal(result, expected)
+
 
 def test_construct_from_kwargs_overflow():
     # GH#55503
diff --git a/pandas/tests/scalar/timedelta/test_timedelta.py b/pandas/tests/scalar/timedelta/test_timedelta.py
index d4398f66e6f89..72747879de4a3 100644
--- a/pandas/tests/scalar/timedelta/test_timedelta.py
+++ b/pandas/tests/scalar/timedelta/test_timedelta.py
@@ -461,7 +461,6 @@ def conv(v):
 
         assert Timedelta("1000") == np.timedelta64(1000, "ns")
         assert Timedelta("1000ns") == np.timedelta64(1000, "ns")
-        assert Timedelta("1000NS") == np.timedelta64(1000, "ns")
 
         assert Timedelta("10us") == np.timedelta64(10000, "ns")
         assert Timedelta("100us") == np.timedelta64(100000, "ns")