The Turner syndrome (TS) phenotype is characterized by a specific neurocognitive profile of normal verbal skills, impaired visual-spatial and/or visual-perceptual abilities, and difficulty with motor function. In the current study, we investigated motor function and nonverbal processing speed in estrogen- and placebo-treated girls (aged 10-12 years) with TS and in age-matched female controls. The goal of this study was to examine whether estrogen replacement therapy would reverse deficits in motor function and in nonverbal processing speed, a measure of the time required to perform certain disparate nonverbal tasks, in adolescent girls with TS. Children received either estrogen (ethinyl estradiol, 12.5-50 ng/kg.day), or placebo for durations of 1-7 yr (mean, 4.0 +/- 2.1 yr) in this randomized, double blind study. Cognitive and motor tasks administered included the Wechsler Intelligence Scale for Children-Revised; nonspatial, repetitive motor tasks (tapping and three tasks from the Paness); and spatially mediated motor tasks [nongrooved pegboard (Lafayette), pursuit rotor, visual-motor integration, and money street map]. Questionnaires administered included the Self-Concept Scale. The major result of this study was the positive estrogen treatment effect on nonverbal processing speed and speeded motor performance in 12-yr-old TS girls. That motor performance would be slower in estrogen-deficient TS females is consistent with previous studies of the influence of estrogen on motor function. Estrogen replacement is thus the most likely explanation for the improved motor speed and nonverbal processing time in the estrogen-treated TS girls compared to that in the placebo-treated TS girls. Whether these findings will influence the psychoeducational outcome or quality of life of females with TS is not yet known.