In this study, daily food and water consumption and body weights, histopathology of placenta, tenascin (TN), type IV collagen and EGF and its receptor immunolocalization in the placenta of albino rats treated with two doses of alcohol (1 and 5 g kg(-1) day(-1)) were determined. Alcohol was administered in three different periods i.e. the whole 4 weeks before the pregnancy, during the pregnancy, and during the 4 weeks before the pregnancy plus pregnancy itself. The samples of placenta obtained from control and treated rats on days 10, 12, 14, 16, 18, 20 and 21 of gestation were evaluated morphologically and fixed for histology and immunohistochemistry. Some differences in food and water consumption between the groups were determined. The placental weight, especially in the groups receiving 1 and 5 g kg(-1) day(-1) alcohol during the pregnancy, showed increases. The changes in placental histology such as increases in the number and the size of trophoblastic giant cells, cytoplasmic dissolution and nuclear polymorphism, degenerations in spongiotrophoblasts, hyperemia at the basal zone and labyrinth, hyperplasia at the labyrinth and irregular vascularization were seen particularly in the groups receiving alcohol during the pregnancy, and during the 4 weeks before the pregnancy plus pregnancy itself. Increases in the immunolocalization of TN and type IV collagen and decreases in the immunolocalization of EGF and EGFR in the placentas of alcohol-receiving rats were found. In conclusion, ethanol treatment during pregnancy in rats affected placentation and the immunolocalization of TN, type IV collagen, EGF and EGFR in the placentas. Copyright (c) 2004 John Wiley & Sons, Ltd.