A Newcastle disease virus lysate of malignant melanoma cells was examined for its possible value in delaying the progression of malignant melanoma with palpable regional node disease (Stage II) to disseminated melanoma (Stage III). This Phase II study was carried out in a group of 32 patients following therapeutic lymphadenectomy. The patients were not prospectively randomized. In each patient, the viral oncolysate was administered subcutaneously at regular intervals over 3 years. The cumulated progressions to disseminated disease at 1, 2 and 3 years were 6%, 8% and 12% of the study group, respectively. These experienced losses were considerably lower than in the control group and in similar control groups described by other investigators. The results suggest that an oncolysate prepared with Newcastle disease virus is a helpful adjunct to surgery in the management of Stage II malignant melanoma.