Developmental behaviors were studied in monkeys subjected to asphyxia at birth. Visual depth perception, visual pla ing, and locomotion appeared significantly later than in nonasphyxiated monkeys. After these behaviors had been established in asphyxiates, however, there was little difference from those observed in normal monkeys. These results were compared with reports of permanent learning deficits that occur in monkeys asphyxiated at birth for similar periods of time. Such comparison suggests that the neural structures responsible for the developmental behaviors studied are not damaged by asphyxia to the same extent as those for acquisition. Delay in development may be an early indication of brain damage with subsequent mental retardation.