diff --git a/doc/source/whatsnew/v0.24.0.rst b/doc/source/whatsnew/v0.24.0.rst
index 3685a24d60e74..463142715e311 100644
--- a/doc/source/whatsnew/v0.24.0.rst
+++ b/doc/source/whatsnew/v0.24.0.rst
@@ -432,6 +432,30 @@ Backwards incompatible API changes
 
 Pandas 0.24.0 includes a number of API breaking changes.
 
+Replacing strings using Pattern
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Be sure to perform a replace of literal strings by passing the
+regex=False parameter to func:`str.replace`. Mainly when the
+pattern is 1 size string (:issue:`24809`)
+
+Before:
+
+.. ipython:: python
+
+    s = pd.Series(['A|B|C'])
+
+    result = s.str.replace('|', ' ')
+    result
+
+After:
+
+.. ipython:: python
+
+    s = pd.Series(['A|B|C'])
+
+    result = s.str.replace('|', ' ', regex=False)
+    result
 
 .. _whatsnew_0240.api_breaking.deps:
 
@@ -1645,6 +1669,7 @@ Strings
 - Bug in :meth:`Index.str.split` was not nan-safe (:issue:`23677`).
 - Bug :func:`Series.str.contains` not respecting the ``na`` argument for a ``Categorical`` dtype ``Series`` (:issue:`22158`)
 - Bug in :meth:`Index.str.cat` when the result contained only ``NaN`` (:issue:`24044`)
+- Bug in :func:`Series.str.replace` not applying regex in patterns of length 1 (:issue:`24809`)
 
 Interval
 ^^^^^^^^
diff --git a/pandas/core/strings.py b/pandas/core/strings.py
index ca79dcd9408d8..f2586602e5498 100644
--- a/pandas/core/strings.py
+++ b/pandas/core/strings.py
@@ -425,7 +425,7 @@ def str_endswith(arr, pat, na=np.nan):
     return _na_map(f, arr, na, dtype=bool)
 
 
-def str_replace(arr, pat, repl, n=-1, case=None, flags=0, regex=True):
+def str_replace(arr, pat, repl, n=-1, case=None, flags=0, regex=None):
     r"""
     Replace occurrences of pattern/regex in the Series/Index with
     some other string. Equivalent to :meth:`str.replace` or
@@ -564,7 +564,7 @@ def str_replace(arr, pat, repl, n=-1, case=None, flags=0, regex=True):
             # add case flag, if provided
             if case is False:
                 flags |= re.IGNORECASE
-        if is_compiled_re or len(pat) > 1 or flags or callable(repl):
+        if is_compiled_re or pat or flags or callable(repl):
             n = n if n >= 0 else 0
             compiled = re.compile(pat, flags=flags)
             f = lambda x: compiled.sub(repl=repl, string=x, count=n)
@@ -577,6 +577,9 @@ def str_replace(arr, pat, repl, n=-1, case=None, flags=0, regex=True):
         if callable(repl):
             raise ValueError("Cannot use a callable replacement when "
                              "regex=False")
+        if regex==None:
+            warnings.warn("Warning: Interpreting '%s' as a literal, not a regex... " % pat + 
+                            "The default will change in the future.", FutureWarning, stacklevel=3)
         f = lambda x: x.replace(pat, repl, n)
 
     return _na_map(f, arr)
@@ -2529,7 +2532,7 @@ def match(self, pat, case=True, flags=0, na=np.nan):
         return self._wrap_result(result, fill_value=na)
 
     @copy(str_replace)
-    def replace(self, pat, repl, n=-1, case=None, flags=0, regex=True):
+    def replace(self, pat, repl, n=-1, case=None, flags=0, regex=None):
         result = str_replace(self._parent, pat, repl, n=n, case=case,
                              flags=flags, regex=regex)
         return self._wrap_result(result)
diff --git a/pandas/tests/test_strings.py b/pandas/tests/test_strings.py
index 7cea3be03d1a7..18acf46eb4c71 100644
--- a/pandas/tests/test_strings.py
+++ b/pandas/tests/test_strings.py
@@ -1008,6 +1008,21 @@ def test_replace(self):
                     values = klass(data)
                     pytest.raises(TypeError, values.str.replace, 'a', repl)
 
+    # GH 24804
+    def test_replace_single_pattern(self):
+        values = Series(['abc', '123'])
+
+        result = values.str.replace('.', 'foo', regex=True)
+        expected = Series(['foofoofoo', 'foofoofoo'])
+        tm.assert_series_equal(result, expected)
+
+    def test_replace_without_specifying_regex_parameter(self):
+        values = Series(['a.c'])
+
+        result = values.str.replace('.', 'b')
+        expected = Series(['abc'])
+        tm.assert_series_equal(result, expected)        
+
     def test_replace_callable(self):
         # GH 15055
         values = Series(['fooBAD__barBAD', NA])
@@ -2924,7 +2939,7 @@ def test_pipe_failures(self):
 
         tm.assert_series_equal(result, exp)
 
-        result = s.str.replace('|', ' ')
+        result = s.str.replace('|', ' ', regex=False)
         exp = Series(['A B C'])
 
         tm.assert_series_equal(result, exp)