While examining the myocardium in conditions of modeling hypothyroidism by performing thyroidectomy, destructive changes and processes of muscle fiber degeneration are observed. After the microwave irradiation with an exposure of 45 minutes, regenerative compensatory restructuring of the structural components of the myocardium of the heart wall occurs. But after thyroidectomy and the microwave irradiation with an exposure of 120 minutes, there is an increase in degenerative and destructive processes in the myocardium of the heart wall. The effect of microwave radiation on the peripheral blood indices of adult rats was studied depending on the exposure time. Animals were divided into 6 groups: after thyroidectomy; after microwave irradiation for 45 minutes; after microwave irradiation for 120 minutes; after thyroidectomy and after microwave irradiation for 45 minutes; after thyroidectomy and after microwave irradiation for 120 minutes; control group. In the control group, peripheral blood parameters did not significantly change during the experiment. In rats that received microwave irradiation with an exposure of 45 minutes, all indicators remained close to normal values. In rats that received microwave irradiation with an exposure of 120 minutes, the following changes were observed: an increase in stab and segmented neutrophils, monocytes, the appearance of young forms of leukocytes, erythrocytopenia, anemia, lymphocytopenia.