Introduction: Anesthetic drugs induce neurotoxic effects during synaptogenesis that cause long-term behavioral disorders. The aim of present study was to investigate the effects of repeated anesthesia in neonate by thiopental on cognitive behavior. Methods: Five-days neonates of Westar rat randomly divided into 3 groups (n=7). Control with no treatment, Sham (saline, i.p.) and Thiopental (30 mg/kg i.p.), injections were performed for 5 constitutive days, anesthesia was continued for 4-5 hours per day in Thiopental group. Infants in the day 19th, and parallel groups after maturation were subjected to Morris Water Maze to measure the time and distance for reaching the Plath form during the all 4 days of learning process. Results: A significant reduction at time and distance during learning was seen as a marker of learning progress before and after maturity in all the groups (P<0.001) however, it was slower in the Thiopental group after maturation in contrast to control and sham animals (P<0.05) Discussion: It has been reported that drugs which affecting stimulatory or inhibitory brain receptors during critical developmental period of nervous system can cause devastating damages. Although thiopental can show neurotoxic effect, its behavioral effects on spatial learning progress showed a decline just after puberty. Persistent effects of infancy thiopental repeated anesthesia may be interfaced with the spatial learning system but due to the significant plastic abilities of the neurons, it didn’t affect the learning progress in the neonatal period.

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