The use of casein hydrolysate in Diamond's axenic culture medium TPS-1 in replacement of trypticase allowed good growth of the trophozoites of Entamoeba histolytica. This modified medium also supported growth of trophozoites preserved for 16 months in liquid nitrogen. Considerable labour and cost of serum can be saved by using 5% instead of 10% bovine serum in combination with this modified medium.