This　paper　presents　equivalent　load　method　for　the　calculation　of　reliability　indices　of　electric　power　generating　systems.　In　this　method　each　unit　model　is　viewed　as　a　load　model　with　state　capacities　represented　by　negative　load　values,　and　sequentially　combined　with　the　load　model.　The　probability　and　frequency　of　each　load　level　are　obtained　after　each　combination.　At　the　end　an　equivalent　load　model　is　obtained　which　yields　the　indices　for　various　margins.　This　method　is　suitable　for　multistate　representation　of　generating　units　and　hourly　load　data　or　load　data　defined　over　any　other　suitable　time　interval　and　is　easy　for　computer　programing.　In　this　method　it　is　not　necessary　to　set　up　a　system　capacity　model,　so　it　greatly　simplifies　the　conventional　method　but　retains　the　same　accuracy.　The　utilization　of　the　proposed　method　is　illustrated　by　a　simple　numerical　example.　The　proposed　method　is　applied　to　the　IEEE-RTS　(IEEE　Reliability　Test　System)　and　several　reliability　indices　are　calculated　and　compared　with　those　obtained　by　other　methods.　Copyright　©　1986　by　The　Institute　of　Electrical　and　Electronics　Engineers,　Inc.