Blood alcohol (ethanol) concentrations in decomposed bodies can mean drinking during life and/or endogenous production after death. The correct interpretation is important in medicolegal cases. This retrospective study of 286 autopsied medical examiner cases was undertaken to evaluate alcohol concentrations and distribution in various fluids and tissues in decomposed bodies. Cases with alcohol present were classified as endogenous production, ingestion, or unable to determine based upon one or more of the following criteria: the presence of ethanol in only one of more than one body fluids, an atypical distribution of ethanol in body fluids, reliable scene or historical information, the presence of C3 alcohols in body fluids. Alcohol was classified as endogenously produced in 55 cases. The presence of alcohol was attributed to ingestion in 130 cases. No alcohol was detected in 39 cases. We were unable to determine the source of the remaining 62 alcohol concentrations. The highest blood alcohol concentration derived from endogenous production was 0.07% in the cases with other fluids negative. The mean blood alcohol concentration was 0.06% and ranged as high as 0.16% in cases having atypical ratios. Alcohol was found in blood and bile while urine and vitreous fluid were negative or had lower concentrations in cases with endogenous production. We conclude that for the majority of cases in which endogenous blood production of alcohol occurs the concentration in blood may be as high as 0.15%.