In this phase la/lb trial, vaccinia melanoma oncolysate (VMO) is a virus-augmented melanoma cell membrane vaccine that has been shown to be safe and to stimulate the production of antimelanoma antibodies in high-risk melanoma patients treated in a surgical adjuvant setting. One patient with stage I and 38 patients with stage II melanoma were entered in the study between December 1984 and October 1985, with a mean follow-up of approximately 17 months. Each patient received a smallpox booster injection followed one week later by the first of 13 weekly intradermal injections of 2.0 mg of VMO. At the end of 13 weeks, injections were given every other week for 12 months or until recurrence. Clinical results show that 25 of the 39 patients had no evidence of disease as of December 1986. Moreover and more importantly, statistical comparison of patients in this study with 39 matched controls shows a significant increase in disease-free survival for the patients treated with VMO. Serum obtained prior to treatment and at three-month intervals during treatment was tested in a Staphylococcus protein A rosette assay for reactivity with melanoma cell lines. All pretreatment samples (39/39) were negative, and 64% became positive by 12 months after appropriate dosage escalations. Moreover, enzyme-linked immunosorbent assay showed a positive correlation between antimelanoma IgG antibody titer and disease-free survival. © 1987, American Medical Association. All rights reserved.