Although previous findings point to the long-term impact of ethanol exposure during periadolescence on hippocampal-dependent learning tasks, comparisons considering different onset and exposure periods during this developmental range of ages are still needed. The aim of this experiment was to determine whether intermittent voluntary chronic ethanol consumption onset at different ages, beginning either in pre-adolescence or adolescence, differentially produces impairment in the hidden-platform-water-maze-task performance persisting in adult rats after a 27-day-long period of abstinence. The performance of two groups of adult Wistar rats of both sexes, whose ethanol drinking onset was at postnatal day 19 (preadolescent) or 28 (adolescent), was compared with that of an adult control non-ethanol exposed group. The results indicated that voluntary intermittent ethanol drinking during the periadolescent period caused dramatic long-term detrimental effects in female rats which were unable to learn. Male rats were also impaired during the initial training blocks, the impact being greater in the group exposed during adolescence, but they exhibited no differences with the non-ethanol exposed control group by the end of training (block 6) and in a probe trial. These data support a greater vulnerability in females during periadolescence and point to adolescence as an especially sensitive period during male development to the long-term detrimental effects of ethanol in learning. (Contains 3 figures and 2 tables.)