This study examined psychological development in 138 children at the age of 6–7 and 10–11 years, who had suffered prenatal radiation exposure at the time of the Chernobyl accident in 1986. These children were compared to a control group of 122 children of the same age from noncontaminated areas of Belarus. The examination included neurological and psychiatric examination, intellectual assessment, and clinical psychological investigation of parents as well as the estimation of thyroid exposure in utero. The exposed group manifested a relative increase in psychological impairment compared with the control group, with increased prevalence in cases of specific developmental speech-language disorders (18·1% vs. 8·2% at 6–7 years; 10·1% vs. 3.3% at 10–11 years) and emotional disorders (20.3% vs. 7.4% at 6–7 years; 18.1 vs. 7.4% at 10–11 years). The mean IQ of the exposed group was lower than that of the control group, and there were more cases of borderline IQ (IQ=70–79) (15.9% vs. 5.7% at 6–7 years; and 10.1% vs. 3.3% at 10–11 years). The mean value of thyroid doses from 131I 0.4 Gy was estimated for children exposed in utero. No correlation was found between individual thyroid doses and IQ at age 6–7 years or 10–11 years. We notice a positive moderate correlation between IQ of children and the educational level of their parents. There was a moderate correlation between high personal anxiety in parents and emotional disorders in children. We conclude that a significant role in the genesis of borderline intellectual functioning, specific developmental disorders of speech, language and scholastic skills, as well as emotional disorders in the exposed group of children was played by unfavourable social-psychological and social-cultural factors such as a low educational level of parents, the break of microsocial contacts, and adaptational difficulties, which appear following the evacuation and relocation from the contaminated areas.