Analysis of heavy metals (Zn, Cd, Pb, Cu, Ni, Fe and Mg) in samples of mussels (Mytilus galloprovincialis) collected during August, July and September 2000 from Oran harbour (polluted site) showed a significant monthly intraspecific variation of the levels of contamination, with a peak of average contamination in July. In addition, comparison of the degrees of pollution according to the mussel coefficients of condition revealed a narrow correlation in particular for zinc, cadmium and iron. This shows the threat in this area of the Algerian coast in terms of marine pollution and its impact, and the risk to human health arising from consumption of heavy metals-polluted mussels bytaking into consideration the detected concentrations of these pollutants if compared with the permissible maximum amounts, particularly for lead.