diff --git a/doc/source/whatsnew/v0.22.0.txt b/doc/source/whatsnew/v0.22.0.txt
index 53b052a955b45..0d177f193b68e 100644
--- a/doc/source/whatsnew/v0.22.0.txt
+++ b/doc/source/whatsnew/v0.22.0.txt
@@ -40,7 +40,7 @@ Backwards incompatible API changes
 Other API Changes
 ^^^^^^^^^^^^^^^^^
 
--
+- :class:`Timestamp` will no longer silently ignore unused or invalid `tz` or `tzinfo` arguments (:issue:`17690`)
 -
 -
 
diff --git a/pandas/_libs/tslib.pyx b/pandas/_libs/tslib.pyx
index a0aae6a5de707..6f534d4acd11a 100644
--- a/pandas/_libs/tslib.pyx
+++ b/pandas/_libs/tslib.pyx
@@ -30,6 +30,7 @@ from util cimport (is_integer_object, is_float_object, is_datetime64_object,
                    is_timedelta64_object, INT64_MAX)
 cimport util
 
+from cpython.datetime cimport PyTZInfo_Check
 # this is our datetime.pxd
 from datetime cimport (
     pandas_datetimestruct,
@@ -68,7 +69,7 @@ from .tslibs.parsing import parse_datetime_string
 
 cimport cython
 
-from pandas.compat import iteritems, callable
+from pandas.compat import iteritems
 
 import collections
 import warnings
@@ -373,12 +374,23 @@ class Timestamp(_Timestamp):
                           FutureWarning)
             freq = offset
 
+        if tzinfo is not None:
+            if not PyTZInfo_Check(tzinfo):
+                # tzinfo must be a datetime.tzinfo object, GH#17690
+                raise TypeError('tzinfo must be a datetime.tzinfo object, '
+                                'not %s' % type(tzinfo))
+            elif tz is not None:
+                raise ValueError('Can provide at most one of tz, tzinfo')
+
         if ts_input is _no_input:
             # User passed keyword arguments.
+            if tz is None:
+                # Handle the case where the user passes `tz` and not `tzinfo`
+                tz = tzinfo
             return Timestamp(datetime(year, month, day, hour or 0,
                                       minute or 0, second or 0,
                                       microsecond or 0, tzinfo),
-                             tz=tzinfo)
+                             tz=tz)
         elif is_integer_object(freq):
             # User passed positional arguments:
             # Timestamp(year, month, day[, hour[, minute[, second[,
@@ -387,6 +399,10 @@ class Timestamp(_Timestamp):
                                       year or 0, month or 0, day or 0,
                                       hour), tz=hour)
 
+        if tzinfo is not None:
+            # User passed tzinfo instead of tz; avoid silently ignoring
+            tz, tzinfo = tzinfo, None
+
         ts = convert_to_tsobject(ts_input, tz, unit, 0, 0)
 
         if ts.value == NPY_NAT:
diff --git a/pandas/tests/scalar/test_timestamp.py b/pandas/tests/scalar/test_timestamp.py
index c1b9f858a08de..9a2e5565ae41b 100644
--- a/pandas/tests/scalar/test_timestamp.py
+++ b/pandas/tests/scalar/test_timestamp.py
@@ -175,6 +175,24 @@ def test_constructor_invalid(self):
         with tm.assert_raises_regex(ValueError, 'Cannot convert Period'):
             Timestamp(Period('1000-01-01'))
 
+    def test_constructor_invalid_tz(self):
+        # GH#17690, GH#5168
+        with tm.assert_raises_regex(TypeError, 'must be a datetime.tzinfo'):
+            Timestamp('2017-10-22', tzinfo='US/Eastern')
+
+        with tm.assert_raises_regex(ValueError, 'at most one of'):
+            Timestamp('2017-10-22', tzinfo=utc, tz='UTC')
+
+    def test_constructor_tz_or_tzinfo(self):
+        # GH#17943, GH#17690, GH#5168
+        stamps = [Timestamp(year=2017, month=10, day=22, tz='UTC'),
+                  Timestamp(year=2017, month=10, day=22, tzinfo=utc),
+                  Timestamp(year=2017, month=10, day=22, tz=utc),
+                  Timestamp(datetime(2017, 10, 22), tzinfo=utc),
+                  Timestamp(datetime(2017, 10, 22), tz='UTC'),
+                  Timestamp(datetime(2017, 10, 22), tz=utc)]
+        assert all(ts == stamps[0] for ts in stamps)
+
     def test_constructor_positional(self):
         # see gh-10758
         with pytest.raises(TypeError):