The pharmacokinetics of sulphadimethoxine were studied following intravenous and oral (single & repeated) administrations. Following a single intravenous injection of 100 mg/kg body weight of sulphadimethoxine in normal chickens, serum concentration-time curve was best described by a two compartments open model with elimination half life (t0.5β), volume of distribution (Vdss) and total body clearance (CLtot) of 5.09 hour, 0.647 L/kg and 0.089 L/h/kg, respectively. Following a single oral administration of 100 mg sulphadimethoxine /kg body weight in normal chickens, the peak serum concentration (Cmax) was 98.07 μg/ml, achieved at a maximum time (Tmax) of 3.01 hour. The mean systemic bioavailability was 99.02 %. The serum concentrations of sulphadimethoxine following repeated oral administration of 100 mg/kg body weight once daily for five consecutive days in normal and experimentally Salmonella Enteritidis infected chickens showed a lower significant value recorded in experimentally Salmonella Enteritidis infected chickens than in normal ones. Sulphadimethoxine showed accumulative behavior in serum of chickens. Results of this study indicated that sulphadimethoxine was useful for treatment of Salmonella Enteritidis infections in chickens. Sulphadimethoxine was assayed in serum, heart, liver, spleen, kidney, fat, breast muscle, thigh muscle, skin, gizzard and brain after 24, 48, 72, 96,120 and 144 hours from the last daily dose of 100 mg sulphadimethoxine /Kg body weight for five days.