Although many investigators have electrically stimulated osteogenesis in vivo, this phenomenon has not been reported in vitro. In this work direct and pulsating currents were applied to in vitro fetal rat tibiae. The results indicated that electric current did cause osteogenesis in vitro, precipitates of calcium compounds formed in the cathode region, and direct current was more effective in stimulating bone growth than pulsed current delivering the same total charge (coulombs).