The role of gangliosides in neuronal differentiation was studied by addition of a mixture of bovine brain gangliosides to cultured neuroblastoma N2A cells. In ganglioside-treated cells the rate and degree of neurite formation was enhanced. Biochemical correlates indicate that the ganglioside-induced morphological differentiation is accompanied by a significant elongation of G1phase, a decrease in the rate of 3H-thymidine incorporation into cellular DNA and an increase of intracellular cAMP content.