The purpose of the study was to determine whether the escape response in a survival situation might not be modified in some way by moderate dosages of CPZ. The procedure used provided two measures, swimming time and success or failure in escaping from a submerged linear runway whose exit was blocked by an oncoming opponent. Three drug levels were selected: 1.0, 2.5, and 4.0 mg/kg CPZ. Measured on the variable of success in the escape situation, the escape response was altered by the administration of CPZ. Measured on the variable of swimming time, the escape response was not altered by the administration of CPZ.