Dogs were exposed to an electromagnetic pulse (EMP) environment 8 hr each day for 45 days. At the end of that time they had received 5.8 × 106 EM pulses at 5 pulses/sec, with a peak electric field intensity of 447 kV/m. Biological tests were conducted to ascertain concentration of erythrocytes, leukocytes, neutrophils, lymphocytes, reticulocytes, and platelets. Bone marrow samples were obtained by biopsy from the ribs 7 days before and 7 days after the last EMP exposure for assessment of mitotic rubricytes and myelocytes. Pregnant female dogs were exposed to the EMP environment in order to study possible gross effects on fetuses. Reproductive capabilities of irradiated male animals were tested for 1 yr after the last exposure. None of these tests revealed any injury in the EMP-irradiated dogs.