OBJECTIVE: The purpose of this trial was to study the effects of chronic resveratrol use on cognitive function in humans. DESIGN: The authors conducted a double-blind, Phase IIa randomized, placebo-controlled trial to obtain preliminary estimates of the effects of resveratrol supplementation on cognitive function over a 90-day period in older adults. LOCATION: University of Florida in Gainesville, FL. SUBJECTS: Sedentary, overweight older adults (N = 32; age range: 65-93 years, M age = 73.34 years, SD age = 7.02 years). INTERVENTION: Participants were randomized to one of three treatment groups (placebo, 300 mg/day resveratrol, 1000 mg/day resveratrol) for 90 days. OUTCOME MEASURES: Cognitive function was assessed before and after treatment using a well-characterized test battery: Trail Making, Digits Forward and Backward, Erikson-Flanker, Controlled Oral Word Association, Hopkins Verbal Learning Test-Revised, and Task Switching. RESULTS: Psychomotor speed improved on the Trail Making Test part A in participants taking 1000 mg/day of resveratrol compared with participants in both the 300 mg/day condition and the placebo condition (p = 0.02). CONCLUSION: This pilot study suggests that 90 days of resveratrol supplementation at a dose of 1000/mg per day selectively improves psychomotor speed but does not significantly affect other domains of cognitive function in older adults. These findings provide modest support to further study the effects of resveratrol on cognitive function in older adults.