Chronic Q fever has been associated with endocarditis, granulomatous hepatitis, and osteomyelitis but only rarely with pregnancy. The apparent predilection of Coxiella burnetii, the organism causing Q fever, for the human placenta suggests that chronic Q fever of pregnancy is due to placentitis. We describe a patient with chronic, clinically apparent Q fever in pregnancy and a successful outcome. The diagnosis was made both by serology and by isolation of C. burnetii from the patient's serum and placenta. Therapy with erythromycin and rifampin contributed to the delivery of a healthy baby. The mother's infection was clinically cured by subsequent therapy with doxycycline and rifampin.