Summary: Pursuant to a congressional request, GAO reviewed the Patent and Trademark Office's (PTO) patent application examination process. GAO noted that: (1) PTO calculation of average pendency includes all issued patents and abandoned applications over a particular period, but does not include applications still under consideration; (2) abandoned applications constituted about 39 percent of the PTO workload in fiscal year 1994 and stayed in the examination process an average of 18.3 months; (3) applications still under consideration had an average pendency of 16 months, but 2.7 percent of these applications had been in process for over 4 years because of delays beyond PTO control; (4) complex inventions and inventions subject to secrecy orders tend to have longer patent pendency periods; (5) foreign applications have slightly longer pendency periods than domestic applications; (6) pendency would have increased on average by 6.7 to 9 months if PTO used original filing dates; and (7) applicants add about 7.4 months on average to the pendency period because of incomplete applications, failure to provide requested information promptly, and failure to pay examination fees.