Abstract Nineteen Puerto Rican patients with malignant melanomas in volar and subungual areas were evaluated to define their clinical and histologic characteristics. Ten were male and nine female, with an age span of 36 to 113 years and a median age of 71 years. Sixteen of the lesions were located on the soles or heels of the feet, and three were subungual. Histologically, all nineteen patients exhibited a radial growth phase diagnostic of acral lentiginous melanoma, and twelve of nineteen were Clark's level IV or V. Tumor thickness fluctuated between 0.27 mm and 13.6 mm, with a total of twelve lesions greater than 6 mm. Eleven patients had regional lymph node enlargement at the time of diagnosis; two had regional skin metastasis and one had metastasis to the liver. Survivals ranged from 7 months to 7 years, with an average duration of 2.76 years and an overall mortality of 66% in those patients after a 3-year follow-up. Based on this study, we conclude that the biologic behavior of acral lentiginous melanoma in Puerto Ricans is similar to that reported in other series, with most of the lesions being deeply invasive and correlating with a poor prognosis.