Dataset for the publication 'Molecular testing of adult Pacific salmon and trout (Oncorhynchus spp.) for several RNA viruses demonstrates widespread distribution of piscine orthoreovirus (PRV) in Alaska and Washington'. This research was initiated in conjunction with a systematic, multi-agency surveillance effort in the United States (U.S.) in response to reported findings of infectious salmon anemia virus (ISAV) RNA in British Columbia, Canada. In the systematic surveillance study reported in a companion paper, tissues from various salmonids taken from Washington and Alaska were surveyed for ISAV RNA using the U.S. approved diagnostic method and samples were released for use in this present study only after testing negative. Here we tested a subset of these samples for ISAV RNA with three additional published molecular assays, as well as for RNA from salmonid alphavirus (SAV), piscine myocarditis virus (PMCV) and piscine orthoreovirus (PRV). All samples (n=2252; 121 stock cohorts) tested negative for RNA from ISAV, PMCV, and SAV. In contrast, there were 25 stock cohorts from Washington and Alaska that had one or more individuals test positive for PRV RNA; prevalence within stocks varied and ranged from 2 73%. The overall prevalence of PRV RNA positive individuals across the study was 3.4% (77 of 2252 fish tested). Findings of PRV RNA were most common in coho (Oncorhynchus kisutch Walbaum) and Chinook (O. tshawytscha Walbaum) salmon. The disease associated with PRV in Atlantic salmon, heart skeletal muscle inflammation (HSMI), has not been reported in Pacific salmon.