Benzotriazoles have been used satisfactorily for the last 25 years as a corrosion inhibitor for copper pipelines. The effect of six benzotriazoles on the crystal growth of calcite was investigated at sustained supersaturation. The rates of crystal growth measured in the presence of benzotriazoles at concentrations of 7.5 x 10(-5) M were drastically increased. The apparent order of the reaction found from kinetic data was n = 2 +/- 0.2, thus suggesting a surface diffusion controlled mechanism.