Alcohol drinking during pregnancy affects structure and function of different organs of the offspringÂs body. Particularly, several parts of the brain are susceptible to harmful effects of alcohol leading to some learning and cognitive problems. The present study aimed to locate a critical period for ethanol induced spatial task impairments in the animals exposed to alcohol during the fetal life. Two month old rats born from mothers treated with alcohol (5.7g/kg) during the first (FH) and second half (SH) and, the first (FQ), second (SQ), third (TQ) and forth quarter (FoQ) of gestational period were subjected to the workingmemory task. The experiments were carried out on an eight arm radial maze across 16 trials. In the first step we found that the animals in the FH group displayed a poor performance compared to their SH counterparts. From these results we concluded that the first half of the pregnancy period is more sensitive to toxic effects of ethanol on the working memory task. The performance of the FQ and SQ groups with the controls demonstrated that only the latter were significantly weak in solving the maze task. The animals related to the TQ and FoQ groups had a similar behavior with the control rats. Comparison of the animalsÂ behavior in all groups also revealed that only the SQ group shows the lowest performance. Consequently the findings of this study demonstrate that drinking alcohol during pregnancy underlies cognitive phenomena in offspring. Noticeably, the second 5 days of the fetal life in rats is more susceptible to deleterious effects of alcohol on the radial maze task.