Ceramide is a postulated intracellular modulator of cell growth and differentiation (Okazaki, T., Bielawska, A., Bell, R.M., and Hannun, Y. A. (1990) J. Biol. Chem. 265, 15823-15831). In order to determine the structural and stereospecific requirements for ceramide effects on HL-60 cells, N-acyl-phenylaminoalcohol analogs were synthesized and evaluated for their ability to mimic the effects of ceramide on cell proliferation and differentiation. These compounds share with ceramide a similar polar headgroup that allows the investigation of the roles of the primary and secondary hydroxyls, the hydrophobicity of the molecule, and stereospecificity. N-Myristoyl derivatives of phenylamino alcohols showed optimal activity over other chain length analogs and were able to mimic the effects of C2-ceramide on cell growth and differentiation. Neither the primary nor the secondary alcohol was necessary for activity, but the amide-linked acyl chain was required. Stereospecificity of action was demonstrated with an enantiomeric pair: D-erythro-N-myristoyl-2-amino-1-phenyl-1-propanol (C14-D-e-APP-1) and L-erythro-N-myristoyl-2-amino-1-phenyl-1-propanol (C14-L-e-APP-1). The D stereoisomer was as effective as C2-ceramide in inhibiting HL-60 cell growth and in inducing cell differentiation, whereas the L enantiomer lacked activity in both assays. These results suggest stereospecific action of ceramide and strongly support a physiologic role for ceramide as an intracellular mediator with primary roles in regulation of cell growth and differentiation.