The effect of administration of cadmium alone in non-irradiated mice as well as the effect of pre-irradiation administration of cadmium on the reparation processes of haemopoiesis were investigated in mice irradiated by a dose of 7.5 Gy. The pre-irradiation administration of cadmium accelerated the reparation processes in the bone marrow and spleen as well as the number of leukocytes and thrombocytes in the peripheral blood. The administration of cadmium alone caused a temporary weight decrease of the thymus and reduced number of erythrocytes, reticulocytes and haemoglobin values in the peripheral blood. The temporary rapid increase in the number of leukocytes on the 21st day after cadmium administration was investigated.