Muscle satellite cells from rainbow trout were exposed in vitro to increasing concentrations of different xenobiotics: copper, dichloroaniline, prochloraz. nonyl-phenol polyethexylate. Mortality and proliferation rate were measured by Hoechst binding and BrdU incorporation. Dose dependent effect of copper on survival and proliferation was observed with an EC50 at 100 muM. A dose dependent effect of nonyl-phenol diethoxylate was observed on survival with an EC50 at 100 muM. This was associated with a biphasic effect on proliferation rate observed both for nonyl-phenol di and poly-ethoxylate: a stimulation of proliferation at low concentration and an inhibition proliferation at large concentration. These effects were related to the inhibition of cells adhesion through the detergent capacity of nonyl-phenol polyethoxylate. The effects of prochloraze and dichloroaniline on cells mortality (EC 50 > 500 muM) and proliferation rate (LOEC: 100 muM) were limited. Whole fish growth, muscle fibre size distribution and satellite cells survival and proliferation were measured on rainbow trout (60-80 g BW) exposed to two concentrations of prochloraze (10 and 100 mug/ml) or nonyl phenol diethoxylate IGEPAL 210((R)) (100 and 400 mug/ml) during 14 and 10 days exposure, respectively. Muscle fibre size distribution and satellite cells proliferation were affected by prochloraz exposure in vivo and this could be related to the alteration in fish feeding status. The exposure to IGEPAL 210((R)) affected the number of satellite cells extracted and induce a biphasic effect on satellite cells proliferation similar to that observed in vivo. The combined exposure to IGEPAL 210((R)) and prochloraze revealed additive effects of these two compounds. The in vivo and in vitro comparison demonstrated that in vitro satellite cells system could be used as a valuable tool to test the effects of pollutants.