Index: Lib/test/test_xml_etree.py
===================================================================
--- Lib/test/test_xml_etree.py	(revision 73267)
+++ Lib/test/test_xml_etree.py	(working copy)
@@ -209,8 +209,25 @@
     >>> check_encoding(ET, "mac-roman")
     """
     ET.XML("<?xml version='1.0' encoding='%s'?><xml />" % encoding)
+ 
+def processinginstruction():
+    """
+    Test ProcessingInstruction directly
 
+    >>> from xml.etree import ElementTree as ET
 
+    >>> ET.tostring(ET.ProcessingInstruction('test', 'instruction'))
+    '<?test instruction?>'
+    >>> ET.tostring(ET.PI('test', 'instruction'))
+    '<?test instruction?>'
+
+    Issue #2746
+
+    >>> ET.tostring(ET.PI('test', '<testing&>'))
+    '<?test <testing&>?>'
+
+    """
+
 #
 # xinclude tests (samples from appendix C of the xinclude specification)
 
Index: Lib/xml/etree/ElementTree.py
===================================================================
--- Lib/xml/etree/ElementTree.py	(revision 73267)
+++ Lib/xml/etree/ElementTree.py	(working copy)
@@ -662,9 +662,9 @@
         # write XML to file
         tag = node.tag
         if tag is Comment:
-            file.write(_encode("<!-- %s -->" % _escape_cdata(node.text), encoding))
+            file.write(_encode("<!-- %s -->" % node.text, encoding))
         elif tag is ProcessingInstruction:
-            file.write(_encode("<?%s?>" % _escape_cdata(node.text), encoding))
+            file.write(_encode("<?%s?>" % node.text, encoding))
         else:
             items = list(node.items())
             xmlns_items = [] # new namespaces in this scope