Normal movement depends in part on the brain's ability to produce and use dopamine, which regulates basal ganglia function. Behavioral, neuroanatomical, and neurophysiological data suggest that the basal ganglia are critical for the performance of sequential movement. Dopaminergic function is modulated by estrogen in animals and in humans. To test the hypothesis that estrogen modulates sequential movement, this study measured the reaction time (RT) and movement time (MT) of 15 women and 10 men in a choice RT task with sequential responses. Higher levels of estradiol in women's blood were associated with faster total movement time (RT plus MT). Testosterone levels in women's blood were not associated with keypressing performance. Hormone levels in men's blood were unrelated to keypressing performance. These results suggest that women's motor performance was affected by hormone levels, and that estrogen may interact with dopaminergic function in women.