In adult animals and man, both acute and chronic ethanol intake is associated with depression of myocardial performance. Accordingly, the cardiac effects of maternal ethanol infusions, in a manner comparable to common obstetric practice of inhibition of premature labor with ethano mighte for inhibition of premature labor, were evaluated in six chronically instrumented fetal sheep. Fetal and ewe arterial PO2, PCO2, and pH values remained within normal limits with infusion rates of 15 c.c. per kilogram of 10 per cent ethanol over two hours (blood ethanol = 110 mg. per cent) and 15 c.c. per kilogram over one hour (blood ethanol = 210 mg. per cent). Fetal instrument evaluation (for 14 to 30 days after operation) provided data concerning pressures and cardiac dimensions which allowed analysis of left ventricular performance. Ethanol produced a significant depression of the extent (p less than 0.01) and velocity (p less than 0.001) of left ventricular myocardial fiber shortening as well as in the mean rate of left ventricular myocardial fiber shortening as well as in the mean rate of left ventricular circumferential fiber shortening (p less than 0.01). These indices of cardiac contractility were depressed in the absence of changes in end diastolic diameter, left atrial pressure, and systemic arterial pressure. Thus, the practice of inhibition of premature labor with ethano6 might contribute to depressed myocardial performance in the neonatal period.