Earlier animal studies suggested that there might be physiologically significant changes in serum calcium following administration of ethyl alcohol. Ionized and total calcium were measured in five normal male subjects following the oral ingestion of 200cm3 of 50% ethyl alcohol. Although blood alcohols reached intoxication levels in all subjects, no significant change in ionized calcium or total calcium occurred. It is unlikely that alcohol contributes to the risks of hypocalcemia or hyperventilation and anxiety in individuals performing in adverse environments, although there is little question it contributes to other risks. Even though two-fold elevations in plasma prolactin have been described in men with chronic alcoholism, no significant changes in plasma prolactin occurred during acute alcohol ingestion. Awareness of the significant increase in plasma osmolality, which has been demonstrated with alcohol, is important to avoid inappropriate therapy, since individuals performing in adverse environments are at risk of becoming dehydrated.