The paper represents some results of a joint commission, organized by the USSR Ministry of Health by order of the USSR Council of Ministers at public requests. The commission worked in the area neighbouring the proving ground at Semipalatinsk in the period of May-July 1988. A radiological situation there was investigated after underground nuclear testing on July 8, 1989. The results of measurements and archive data were used to estimate doses of radiation exposure of the population in the period of 1949 (nuclear testing on the ground and in the atmosphere) and in the period of underground testing, It was shown that in the period of 1949-1963 approximately 10,000 people received increased doses of external and internal irradiation. A high level of radiation-induced chromosome aberrations was noted among them. The highest effective equivalent doses of external and internal irradiation were received by the residents in the villages of Folon' (1.6 Gy during the first testing in 1949), Karaul (0.37 Gy), Sarzhal (0.20 Gy), Semenovka (0.02 Gy). The annual effective equivalent doses at that period did not exceed 0.0056 Gy (the highest value) for the Semipalatinsk residents. Proceeding from the values of collective doses probable long-term effects (malignant tumors) were assessed. Recommendations and conclusions of the commission are presented.