The nuclear industry has had a variety of reliability problems with pressurized water reactor steam generators. Most of these problems have been associated with corrosion and mechanically induced damage, including secondary water intergranular corrosion and stress corrosion cracking (SCC), primary water SCC, wastage, high cycle fatigue, and fretting and wear of the Inconel 600 or Incoloy 800 tubes, plus accelerated corrosion of carbon steel tube support structures in crevice regions. Corrosion and mechanically induced damage are caused by complex interactions of water chemistry, thermal-hydraulic design, materials design choices, fabrication methods, and secondary plant materials, design, and operations. Corrosion has affected almost 90% of steam generators operational prior to 1977, resulting in forced and scheduled outages to plug or sleeve tubes and repair or replace generators. Utility operators have begun to respond vigorously with improved operating and maintenance procedures that reduce air and cooling water inleakage; with installation of full-flow condensate polishers, titanium or stainless steel condensers, retubed feedwater heaters, and moisture separater reheaters; and with modifications to makeup water and blowdown systems. The Steam Generator Owners’ Group continues to provide a focus for development work to understand damage mechanisms, provide remedial actions, and effect transfer of technology to the utility operators