Field investigations on Perna perna were carried out in 1999 in an unpolluted site (Cap Ghir) and a wastewater-polluted site (Anza) to determine the contents of glycogen, lipids and proteins in mussel samples collected every month. Sample analyses were made using the entire soft masses of male and female mussels or their gonads only. Compared to unpolluted P. perna, the glycogen and lipid concentrations found in polluted mussels showed significantly quantitative variations throughout the year; in contrast, insignificant differences were only found for protein concentrations. Female gonads contained higher rates of lipids than male ones, whereas protein contents were similar. In contrast, in entire mussels, females were richer than males, whatever the biochemical parameter considered. Apart from protein rates in December, most of highest concentrations were noted from October to November. Contrary to unpolluted mussels (of which storage components were constituted by glycogen and lipids), a different reserve strategy, mainly based on the use of lipids, followed by that of proteins would exist in the P. perna from the polluted bed.