A series of new 3-alkyl-1-(1-methyl-2-phenylethyl)ureas related to ceramide was synthesized and evaluated for their in vitro cytotoxic activity against five human tumor cell lines. The urea analogue (2b) of 813 showed comparable or slightly more potent cytotoxic activity as compared to B13, indicating that urea does appear to serve as a bioisostere of amide.