Several alkyl phosphorylcholines and related derivatives were tested against Leishmania donovani amastigotes in mouse peritoneal macrophages in vitro and ED50 values were determined in the range of 1-12 microM. The three alkyl phosphorylcholines tested against L. donovani in BALB/c mice were active, an ED50 of 12.8 mg/kg/day X 5 was ascertained for one compound, but an alkyl phosphorylethanolamine was inactive.