Regional node dissection is practiced as a measure of prophylaxis in patients with stage I and II malignant melanoma. Although the drainage pattern of the extremities is obvious, in the head and neck and trunk it may be ambiguous.We have used lymphoscintigraphy to assist in delineating the lymphatic drainage in 22 patients with primary malignant melanoma. Fourteen patients had melanoma in the head and neck region, and eight had melanoma in the trunk region. Based on Clark's classification there were ten level III melanomas, eight level IV melanomas, and two level V melanomas; the levels of the remaining two melanomas were unspecified. Seven melanomas were between 0.76 and 1.5-mm thick, eleven were between 1.51 and 4.0-mm thick, and two were over 4.0-mm thick (the remaining two were unspecified). Regional nodes were clinically negative in 18 patients. The scan distribution was unexpected in 13 patients (59%), and it influenced the surgical procedure in 11 patients (50%).No patient incurred an adverse effect from the scan. We conclude that lymphoscintigraphy may be of value in guiding prophylactic lymph node dissection in melanoma patients.