The 96-h LC50 value of cadmium chloride (CdCl2 . H2O), a metal salt widely used in industry, was determined in the water frog (Rana ridibunda Pallas, 1771). The experiments were conducted in two series and a total of 140 frogs were used to determine acute toxicity. In addition, behavioral changes in the water frog were determined for each cadmium chloride concentration. Data obtained from the cadmium chloride investigation were evaluated by using the probit analysis statistical method and the 96 h LC50 value for water frog was estimated to be 51.2 mg/l. (C) 2003 Elsevier Science Ltd. All rights reserved.