Fourteen (2-chloroethyl)nitrosourea congeners of L-amino acid amides have been synthesized as potential antineoplastic agents. Almost all the congeners tested were found to be highly active against experimental leukemia L1210 in mice. The chemical decomposition rates of the congeners were measured in a buffered solution (pH 7.4) at 37 degrees C. Acute toxicities of some of the congeners were determined for mice. The congener of sarcosinamide shows the longest half-life (T0.5 = 329.7 min) and the lowest toxicity, LD50 = 392.0 mg/kg (ip) and 426.6 mg/kg (iv), in this series.