Aim: The effects of renal failure on the pharmacokinetics of sulphamethoxazole were investigated after oral administration of 100 mg/kg of the drug using a mice model of mercury chloride-induced renal failure. Materials and Methods: Mercury chloride was given to mice at the doses of 3 and 6 mg/kg. Plasma sulphamethoxazole concentrations were measured by spectrophotometer. Plasma concentration-time data were fitted to a two-compartment open model. Results: Significant findings (p<0.05) were observed for absorption (AUC and t_1/2a) and elimination (t_1/2β and MRT) phases of sulphamethoxazole related with renal failure. Also area under the curve value decreased, and mean residence time value increased with renal failure (p<0.05). Conclusion: Study result showed that dosage and administration intervals of sulphamethoxazole were important for patients with renal failure.