A survey of 80 reservoirs in the United States with striped bass Morone saxatilis populations indicated some summer mortality of the species in 27 (34%) of the impoundments. Most of the reported mortality was of medium sized to large adults (> 5 kg). More mortality was reported in July-September than in other months. Reservoirs for which summer striped bass mortality was reported had significantly greater mean surface area, volume, maximum depth, and depth of water release than those without reports of striped bass mortality. However, the presence or absence of reported striped bass mortality bore no discernible relationship to reservoir morphometric or limnological features when 20 such characteristics were examined by multivariate analysis. The results suggest overall that summer mortality of striped bass is widespread geographically in reservoirs of the United States, but its occurrence is highly variable and by no means universal.