Objective To evaluate the curative effect of normobaric oxygen therapy on fetal atrial premature contractions(PACs) with Doppler ultrasound. Methods Maternal normobaric oxygen therapy was performed in one hundred and seventy three fetus with PACs but without congenital heart disease diagnosed by Doppler echocardiography. Another 63 cases with isolated PACs receiving no therapy served as controls. Results (1) The average ratio of full recovery in the second course of treatment was 97.8 % in one hundred and seventy three fetus with PACs; (2) The valves′ regurgitation volume reduced or disappeared, the pericardial edema′s volume reduced or absorbed and the peripheral blood flow improved obviously (P