A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2010 Bering Sea groundfish trawl fishery was undertaken to determine the overall stock composition of the sample set. Samples were genotyped for 11 microsatellite markers and results were estimated using the current chum salmon microsatellite baseline. In 2010, genetic samples were collected as part of the species composition analysis of the Alaska Fisheries Science Centers North Pacific Observer Program. This sampling change for 2010 was an interim measure implemented until the systematic sampling protocols are finalized. Consequently, stock composition estimates apply to the sample set and may not represent the entire chum salmon bycatch. Based on the analysis of 1,048 chum salmon bycatch samples collected throughout the 2010 Bering Sea trawl fishery, East Asian (38%), North Asian (26%), Western Alaska (14%), and Eastern Gulf of Alaska/Pacific Northwest (13%) stocks dominated the sample set, with smaller contributions from Upper/Middle Yukon River (7%) stocks. The estimates for the 2010 chum salmon bycatch sample set were similar to the 20052009 chum salmon bycatch estimates, suggesting consistency of the regional stock contributions across years. Analysis of temporal groupings within the groundfish B season revealed changes in stock composition during the course of the season with decreasing contribution of Western Alaska and Eastern Gulf of Alaska/Pacific Northwest stocks and increasing contribution of North Asian stocks over time, but leaves unanswered whether these changes are due to temporal or spatial differences in the sample set.