Reaction time (RT) studies reveal that vocal responses present an exception to the pervasive finding of slowed performance in aged adults. Previous vocal RT studies that compared young and aged speakers elicited a single-word response. Inconsistent findings may be attributed to their use of a limited range of response complexity. Young speakers show a significant increase in vocal RT from vowel to sentence responses [Watson et al., J. Voice 5, 18--28 (1991)]. This study tested the hypothesis that aged speakers in good physiologic condition show significantly longer vocal RT values relative to young speakers as responses increase in complexity. Vocal RT was recorded for isolated vowel, word, and sentence responses. The simple RT paradigm included variable foreperiods and intertrial intervals. Young subjects ranged from 24--31 yr. Aged subjects ranged from 68--85 yr. Group, response, and group x response effects were significant. Post hoc comparisons revealed significant between-group vocal RT differences for the word and sentence responses. Consideration of peripheral and central factors that may underlie the response complexity effect on vocal RT in aged speakers supports the conclusion that the origin of the complexity effect resides in central linguistic and/or motor planning for the response.