The Incident Reporting System (IRS) is an essential element of the international operating experience feedback system for nuclear power plants. IRS reports contain information on events of safety significance with important lessons learned. These experiences assist in reducing or eliminating recurrence of events at other plants. The IRS is jointly operated and managed by the Nuclear Energy Agency (NEA) and the International Atomic Energy Agency (IAEA), a specialised agency within the United Nations system. This report highlights important lessons learned from events reported to the IRS over the period of July 1996-June 1999. A total of 342 events were reported by the participating countries during this time. Several areas were selected in this report to show the range of important topics available in the IRS. These include several different types of failure in a variety of systems, as well as experience of human errors in combination with system failures. It is important that sufficient national resources be allocated to enable timely reporting of events important to safety, and to share these events in the IRS database. This report is intended to provide general information for senior officials in industry and government who have decision-making roles in the nuclear power industry.