The effect of total asphyxia on dendritic development of the pyramidal cells in the mouse cerebrum was investigated using the Golgi-Cox method. Although neonatal asphyxia did not alter the number of basal dendrites arising from the cell bodies, the dendrites in the 20-day-old treated animals were significantly shorter than those in the controls. Even at 60 days, the number of longer dendrites in the treated mice was significantly less than that in the controls.