Background and Purpose In hemiparetic individuals, low endurance to exercise may compound the increased energy cost of movement and contribute to poor rehabilitation outcomes. The purpose of this investigation was to describe how hemiparetic stroke patients responded to intense exercise and aerobic training. Methods Forty-two subjects were randomly assigned to an exercise training group or to a control group. Treatments were given three times per week for 10 weeks in similar laboratory settings. Baseline and posttest measurements were made of maximal oxygen consumption, heart rate, workload, exercise time, resting and submaximal blood pressures, and sensorimotor function. Results Only experimental subjects showed significant improvement in maximal oxygen consumption, workload, and exercise time. Improvement in sensorimotor function was significantly related to the improvement in aerobic capacity. After treatment, experimental subjects showed significantly lower systolic blood pressure at submaximal workloads during the graded exercise test. Conclusions We conclude that hemiparetic stroke patients may improve their aerobic capacity and submaximal exercise systolic blood pressure response with training. Sensorimotor improvement is related to the improvement in aerobic capacity.