BACKGROUND: The incidence of cutaneous malignant melanoma continues an increasing trend worldwide and has had the highest rise in incidence of all malignancies during the last decades. Mortality rates for melanoma have remained relatively stable in most countries despite the increase in incidence rates. The purpose of this study is to describe the epidemiological trends of malignant melanoma in Puerto Rico from 1987 to 2002 and to compare these findings with those previously reported for Puerto Rico as well as with those reported for other countries. METHODS: All cases of malignant melanoma reported to the Puerto Rico Cancer Registry from 1987 to 2002 were included. Age-adjusted incidence and mortality rates were calculated. Trends were compared by age, gender, anatomical location of the tumor and tumor thickness. RESULTS: There were 1,568 new melanoma cases reported between 1987 and 2002 in Puerto Rico, comprising a 50% overall increase in incidence during this period. Male to female incidence ratio was 1:0.86. The most common anatomical location in women was the lower extremity followed by the head and neck region. In men, the most common anatomical location was the trunk, followed by the head and neck region. Most of the superficial tumors (< 1mm) were located on the trunk followed by the lower limb. The most common specific histologic diagnosis reported was melanoma in situ. In 40.8% of the cases the tumor thickness value was not provided. The number of thinner melanomas (< 1mm) reported increased during the study period. Mortality rates were slightly higher for men than for women, still mortality rates remained stable for both genders and all age groups analyzed. CONCLUSIONS: Melanoma incidence rates continue to increase in Puerto Rico. This, in combination with an increase in the diagnosis of thin melanomas, suggests that the stable mortality rates may be due, in part, to earlier diagnosis and improved overall prognosis.