Scopolamine and placebo transdermal patches were applied on alternating days to 12 normal volunteer subjects. Psychological performance tasks, physiological assessments, a subjective feeling state questionnaire, and a sleep questionnaire were completed each day. Transdermal scopolamine produced significant decrements in memory task performance, daytime feelings of alertness, ease of waking, and alertness following waking, while resting heart rates were lowered. Significant drug × patch number interaction effects were present with memory for new information, letter cancellation omission errors, rapid visual information processing reaction time, and self-rated ease of getting to sleep, but there was no consistent pattern to the changes following successive patches. Visual problems (blurred vision, longer visual near point) increased following successive scopolamine patches, but the changes in task performance were not related to these visual changes