Abstract Crossland and Leonard (1963) first reported that the white rat will develop physical dependence on sodium barbital if fluid intake is restricted to solutions containing increasing concentrations of that drug. Convulsions occurred in such rats following the withdrawal of sodium barbital. The study reported here was based on the same method. Two groups of male Wistar rats were addicted to mean final dose levels of 396 mg/kg in 111 days (Group I) and 313 mg/kg in 159 days (Group II). Both groups of rats were hypothermic at the end of addiction, and Group I rats lost a significant amount of weight during the same period. Following barbital withdrawal both generalized tonic-clonic and partial convulsions were observed. Other manifestations of abstinence were reduction in food and water consumption as well as weight loss. Perhaps the continuous availability of barbital and its more frequent intake favors the development of physical dependence. Previous unsuccessfulattempts to induce in rats physical dependence on the barbiturates were based on the single daily dose method of administering the drug.