Hindsight bias refers to the tendency to judge events leading to an adverse event as errors because the bad outcome is already known, thus describing the outcome as preventable. This study presented anesthesia providers with two case scenarios—one which stated the diagnosis at the beginning of the scenario (hindsight) and one which did not (foresight). Providers assigned higher probability to the diagnosis in the hindsight scenarios than in the foresight scenarios. When providers review adverse events, they should consider the impact of hindsight bias in interpreting clinical outcomes.