The hydrolysis by Clostridium perfringens (welchii) phospholipase c [EC 3.1.4.3] of ceramide 2-aminoethylphosphonate (CAEP) and sphingo-ethanolamine (Sph. EA), which are analogues of sphingomyelin, was studied. 2-Aminoethylphosphonic acid (ciliatine) and ceramide produced from CAEP by the phospholipase c, together with phosphorylethanolamine and ceramide from Sph.EA were isolated in crystalline form, and identified.