In this study, effects of cation exchanger zeolite on the accumulation of lead in muscle, liver, gill and kidney of Nile tilapia (Oreochromis niloticus) were investigated. The fish were exposed to 0.1 mg/l Pb, 0.1 mg/l Pb + 0.1 g/l zeolite, 0.1 mg/l Pb + 0.2 g/l zeolite and 1.0 mg/l Pb, 1.0 mg/l Pb + 0.1 g/l zeolite and 1.0 mg/l Pb + 0.2 g/l zeolite mixtures for 10, 20 and 30 days, lead accumulation in tissues were measured by atomic absorbtion spectrophotometry. Lead accumulation increased with increasing concentrations of lead in the medium and with increasing periods of exposure tissues studied. All tissues lead accumulation was found to be statistically significant in the 0.1 and 1.0 mg/l of lead concentrations at 10, 20 and 30 days. Highest accumulation occurred in the kidney followed by gill, liver and muscle. In all exposure period, accumulation of lead in whole tissues of O. niloticus decreased in the presence of zeolite. In both mixed exposure (lead + zeolite) concentrations, zeolite significantly reduced the accumulation of lead in the kidney and liver of O. niloticus.