We studied the time course of caspase-3 activity in the hippocampus of rat pups characterized by different efficacy of performance, i.e., number of escapes, induced by a brief footshock (40 V) on the 13th postnatal day (PND). The pups could escape footshock by crossing an open door (EF group). After crossing, the stimulation was stopped and resumed within 1 min until the total time of footshock reached 200 s. The data for the EF group were compared with the data of passive control group. The second control group included rat pups subjected to inescapable stimulation (IF group). Immediately after the stimulation, hippocampal caspase-3 activity was decreased in the EF group; this effect was not observed in the IF group. The lowest enzyme activity was found in the hippocampus of the animals with the largest number of escapes. By PND 17, the caspase-3 activity in the hippocampus of the “most successful” pups reached the control level and, in the IF group, the caspase-3 activity was suppressed. Thereafter (21-26 PND), the caspase-3 activity significantly increased in the EF group, but not in the IF group. The maximum caspase-3 levels was found in the hippocampus of the most unsuccessful rats (1-2 escapes).