Five groups of ovariectomized rats were tested during in vivo microdialysis, and concentrations of dopamine (DA) and its metabolites were determined in dialysate. In striatum, DA increased more in hormone-primed ovariectomized female rats pacing copulation than in those engaging in sex that could not pace, those that were hormone primed but tested without a male present, or oil-treated groups (p < .02). Administration of estrogen before microdialysis resulted in enhanced striatal DA in response to a male rat relative to the animals tested without a male (p < .06). Female rats that were pacing sexual behavior also exhibited a greater increase in accumbens DA than did the no-male, estrogen-primed, or oil-treated groups (p < .015). Nonpacing animals displayed a significant decrease in DA from accumbens 30 min after introduction of the male rat (p < .05) but otherwise were not different from pacing animals. Estrogen-treated animals also had an enhanced increase in accumbens DA compared with oil-treated rats (p < .05). These data suggest that DA release in the striatum and accumbens is dependent on the context in which sexual behavior occurs and that estrogen may in part modulate these dopaminergic responses.