Adequate levels of physical activity (PA) have been associated with the promotion of health and prevention of disease. In recent years different investigations have found differences between ethnic groups in terms of their levels of PA. However there has been little data regarding the PA levels of island Puerto Ricans. The purpose of this study was to investigate the differences in quantity and intensity of leisure time PA in regularly active adults in Puerto Rico. Three hundred ninety seven male (206) and female (191) volunteers between the ages of 18 and 76 years, engaging in regular voluntary PA in public recreational facilities in the main metropolitan area in Puerto Rico participated in the study. Demographic, anthropometric and PA variables were ascertained through direct interview with participants on a day in which they conducted their regular activity, and after completing an informed consent form. Variables measured included age, gender (GEN), weight (WT), body mass index (BMI), minutes of activity (MINACT), minutes of vigorous activity (MINVACT), Pre and post exercise heart rate (HRPRE, HRPOS), ratings of perceived exertion (RPE) and estimates of caloric expenditure (calories, CAL; activity counts ACTCAL) as measured with a Caltrac activity monitor. Independent t-tests were used to compare males and females on the PA variables. Additionally, regression analysis was used to try to predict PA variables. All tests were conducted at the 0.05 level of significance. Significant differences were found between men and women in: WT t (1,389) = 8.102, CAL t (1,157) = 4.527 and ACTCAL t (1,154) = 4.537. Using multiple regression it was possible to predict MINACT and MINVACT for males. MINACT = 32.743 + 1.326(BMI) – 1.596(HRPRE) and MINVACT = 43.830 + 1.020(BMI) – 2.083(HRPRE). It was not possible to predict the PA variables for females. It was concluded that although males and females in the sample were similar in demographic and some PA variables, individual characteristics seem to explain differences in the amount and intensity of their regular PA. Keyword(s): adult physical activity/fitness, exercise/fitness/physical activity, multiculturalism/cultural diversity