Pharmaceuticals and personal care products (PPCPs) form part of the new generation of pollutants present in many freshwater and marine ecosystems. Although environmental concentrations of these bioactive substances are low, they cause sublethal effects (e.g., enzyme inhibition) in non-target organisms. How-ever, little is known on metabolism of PPCPs by non-mammal species. Herein, an in vitro enzyme trial was performed to explore sensitivity of carboxylesterase (CE) activity of aquatic organisms to fourteen PPCPs.The esterase activity was determined in the liver of Mediterranean freshwater fish (Barbus meridionalisand Squalius laietanus), coastal marine fish (Dicentrarchus labrax and Solea solea), middle-slope fish (Tra-chyrhynchus scabrus), deep-sea fish (Alepocephalus rostratus and Cataetix laticeps), and in the digestivegland of a decapod crustacean (Aristeus antennatus). Results showed that 100 M of the lipid regulatorssimvastatin and fenofibrate significantly inhibited (30–80% of controls) the CE activity of all target species.Among the personal care products, nonylphenol and triclosan were strong esterase inhibitors in mostspecies (36–68% of controls). Comparison with literature data suggests that fish CE activity is as sensitiveto inhibition by some PPCPs as that of mammals, although their basal activity levels are lower than inmammals. Pending further studies on the interaction between PPCPs and CE activity, we postulate thatthis enzyme may act as a molecular sink for certain PPCPs in a comparable way than that described forthe organophosphorus pesticides