The effects of ethanol intake were studied in the three groups of Fischer strain rats. The EtOH-F group began drinking freely at 29 days of age and continued all through mating, pregnancy, delivery, and lactation days. They drank a 10% aqueous solution of ethanol, with net ethyl alcohol 9.7 g/kg b. w. on average. The EtOH-P group drank a 20% aqueous solution of ethanol for the first time on the first day of pregnancy. The solution was then given periodically once a day, oral net ethyl alcohol 3.8 g/kg b. w., through gestation, labor, and lactation. The control group was not exposed to ethanol. Comparative observation were made on both maternal rats and their offspring. 1) Maternal rats: Maternal body weight gain between the first and 20th days of pregnancy was significantly low in the two drinking groups (EtOH-F:p less than 0.01, EtOH-P:p less than 0.01), compared with the control group. Comparing the EtOH-F and the EtOH-P, it was found that body weight gain during the 20 days of pregnancy was significantly depressed in the former group (p less than 0.05). There were no significant differences in placental weight among the three groups. Histological findings disclosed that the brain, liver, and kidney had moderate changes in the EtOH-F, whereas the control showed only slight changes. 2) The average number of fetuses at the 20th day of gestation, neonates per litter, did not significantly different among the three groups. The body weights of fetuses at the 20th day of gestation, of neonates and 10-day-old offspring were recorded. In the case of the EtOH-P group, significantly low values (p less than 0.05, p less than 0.01, p less than 0.01) compared with the respective controls. In the case of the EtOH-F group, the differences were non-significant, p less than 0.01 and p less than 0.01 respectively. 3) Histological study of the brain, lung, liver, kidney, and thymus in offspring revealed that remarkable visceral immaturity and hemorrhage were in the EtOH-P and the EtOH-F groups as compared to the control, and they were more pronounced in the EtOH-F group than in the EtOH-P group. 4) Different ways of ethanol administration brought about different results: The EtOH-P group showed a clearer tendency to have low-body-weight of offspring than those the EtOH-F group.(ABSTRACT TRUNCATED AT 400 WORDS)