A comparative retrospective study of patients with primary malignant melanomas of the extremities, Clark level IV/V and tumor thickness greater than or equal to 1.5 mm, was performed in Sydney (Australia) and Groningen (The Netherlands). The efficacy of wide local excision combined with adjuvant regional perfusion (Groningen) was compared with that of wide surgical excision only (Sydney). Patients were classified by sex and tumor location. There were only sufficient numbers of female patients with a tumor of the lower extremity available for this comparative study. All patients were stage I and none received prophylactic lymph node dissection. Age, tumor location, tumor thickness, depth of infiltration and ulceration were taken into account and the factors studied within this group were 10-year disease-free rate, 10-year survival rate, and local and regional recurrences. Women with a melanoma of the leg (excluding the foot) who had been treated by excision and adjuvant regional perfusion, had a significantly better 10-year disease-free rate (P less than 0.0005), a significantly higher 10-year survival rate (0.010 less than P less than 0.025) and significantly fewer local/regional recurrences (P less than 0.0005) than women treated by wide local excision only. For tumors of the foot, however, no significant differences in 10-year disease-free rate, 10-year survival rate or local/regional recurrences were observed after perfusion.