Mean arterial pressure (MAP) and heart rate (HR) were studied in 12 hypotensive preterm neonates given dopamine. A significant, although temporary, elevation in MAP (8 +/- 3 mm Hg; p less than .01) occurred in five neonates in response to 5 micrograms/kg.min, but an increase in MAP was found in all infants (11 +/- 6 mm Hg; p less than .01) when the infusion rate was doubled. This elevation was sustained only in five who previously showed some response to the slower infusion. HR was unaffected except for an increase of 22 +/- 12 beat/min (p less than .01) in the five showing sustained MAP elevation with 10 micrograms/kg.min. Dobutamine failed to raise MAP in the seven who relapsed, and refractory shock resulted. We conclude that time should not be wasted when starting dopamine at less than 10 micrograms/kg.min in hypotensive preterm infants, as lower rates are unlikely to produce a response and delay may cause further compromise.