The purpose of the investigation is the study of dose-response relationship at the antenatal exposure of low level ionizing radiation (137Cs, 1.0-1.25; 1.7-1.9 and 2.3-2.5 Gy during 20 days). The decrease of body weight in pregnant females and antenatal embryonic mortality at the doses 2.3-2.5 Gy are revealed. Physical postnatal anomalies with decrease of the adaptation were estimated by the strength endurance after antenatal exposure of gamma-rays at the doses of 1.0-2.5 Gy.