We investigated cardiovascular and metabolic responses in 23 healthy pregnant volunteers in their third trimester prior to, during, and after a 15-minute period of treadmill exercise. The energy utilization of this exercise was 2.33 MET with an oxygen consumption under 0.5 L/minute. Exercise induced a significant increase in maternal heart rate and a shortening of the R time intervals; both returned to baseline by 30 minutes of recovery. This light exercise also induced a significant increase in glucagon, norepinephrine, and epinephrine concentrations, all of which were transitory and reversed within 30 minutes of the recovery period. No change in glucose or cortisol concentration resulted from this exercise. We conclude that light exercise of brief duration elicits appropriate and transitory cardiovascular and metabolic responses in normal pregnancy.