To determine if dopamine would prevent the renal side effects of indomethacin, fifteen preterm infants were randomized into two groups: seven received indomethacin alone, and eight received indomethacin together with low dose dopamine infusion. Infants who received indomethacin together with dopamine had significantly higher UV (p less than 0.005), CNa (p less than 0.005), Cosm (p less than 0.005) and FENA (p less than 0.005) than those of infants who received indomethacin alone. There was, however, no significant difference in Ccr and FNa between the groups. These data indicate that dopamine overcomes indomethacins renal side effects of tubular origin, but it cannot prevent the renal vasoconstrictive action of vasoconstrictor hormones following the inhibition of prostaglandin synthesis by indomethacin. Considering that RBF and GFR turn to normal approximately 12 hours after the last dose of indomethacin, and that with the use of dopamine systemic blood pressure and peripheral circulation can also be normalized and to some extent myocardiac contractility improved, low doses of dopamine can be used instead of furosemide in the sick preterm infant with PDA when indomethacin therapy is indicated.