Heavy metal (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) concentrations were determined by ICP-AES in Ostrea equestris from three beaches (Barra do Furado, Buena, and Ponta do Retiro) on the northern coast of Rio de Janeiro State. The average concentration was 0.8 +/- 0.18, 0.4 +/- 0.21, 58 +/- 25.6, 249 +/- 52.3, 11 +/- 1.31, 0.55 +/- 0.16, 0.13 +/- 0.11, and 1131 +/- 321 microg x g(-1) dry weight for Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn respectively. Significant spatial variation (p < 0.05) between the samples areas occurred for Cr, Pb, and Zn with higher values in Barra do Furado; and for Cu in Ponta do Retiro. Significant temporal variations (p < 0.05) were observed for all metals except Cu. Temporal variability may be related to changes in the inputs of metals associated with suspended particles. Concentrations were similar to those found in areas under low pollution impact, except for Zn, the high concentrations of which probably reflect the physiological characteristics of these organisms.