Abstract Copolymers of tributyltin methacrylate (M 1 ) with cyclohexyl methacrylate, ethoxyethyl methacrylate, ethyl methacrylate, 2‐hydroxyethyl methacrylate, and 2‐hydroxypropyl methacrylate were synthesized in solution at 55°C utilizing azobisisobutyronitrile initiator. Copolymer compositions were determined by tin analysis; monomer reactivity ratios were calculated by Kelen‐Tüdös method. Since the reactivity ratios indicate the distribution of different monomer units in the polymer chain, the measured values are compared and discussed. Preliminary results of the biotoxicity studies on some of the copolymers are also reported.