One hundred and thirty patients with various neoplastic disorders were treated with uracil-mustard (U-8344), a new oral alkylating agent with a therapeutic spectrum similar to that of other mustard analogues. This agent was especially effective in treatment of lymphomas and chronic leukemias. Occasionally solid tumors, notably ovarian carcinoma, responded. Advantages of uracil-mustard over other similar agents are: (1) the small dosage required to obtain beneficial results; (2) uniform tolerability; and (3) simplicity of the regimen. With judicious administration long-term therapy may be carried out with continued benefit. The study suggested that the drug may be of value when other alkylating agents have failed.