AbstractTwo phagocytes-mediated activities of the sea bassDicentrarchus labraxwere examined after exposure to sublethal concentrations of copper and cadmium: (a) phagocytosis (measured by phagocytotic index), and (b) the production of reactive oxygen intermediates (luminoldependent chemiluminescence) in response to bacteriaAeromonas salmonicida. In vivoexposure for 48 h to each metal separately by intraperitoneal injection did not affect the quantity of phagocytes of pronephros and their viability but inhibited, in dose-dependent manner, phagocytosis and chemiluminescence of these cells. The half-inhibition value was 250µ;gkg−1for copper and 1 mgkg−1for cadmium.In vitroexposure to copper for 30 min had the same immunomodulatory effect on macrophage chemiluminescence as that observedin vivo, whereas treatment with cadmium under the same conditions had a dose-dependent effect opposite to that observedin vivo.Assessement of these two macrophage-mediated functions could therefore be used as early bioindicators of the marine pollution.