The effects of a single 10 mg dose of the new H1 antihistamine mizolastine on psychomotor performance and memory in the elderly were assessed in a double-blind, cross-over, placebo-controlled study in 15 elderly female volunteers aged 66-77 years, using clemastine 2 mg as a positive control. Objective (critical flicker fusion, choice reaction time, digit symbol substitution, immediate and delayed free recall) and subjective (linear analogue rating scales) assessments were done on each test day before the dose, then 4 and 8 h post-dose. Plasma samples were also collected. A single oral dose of mizolastine within the range of recommended daily therapeutic dosages (10 mg) failed to induce subjective drowsiness and produced no detrimental effects on psychomotor performance or on short-term and long-term memory in the elderly subjects. In contrast, 2 mg clemastine induced significant impairments (decrease in critical flicker fusion, increase in recognition reaction time) in comparison with placebo and mizolastine, although it did not impair memory. The pharmacokinetic profile of mizolastine in the elderly study subjects was similar to that observed in healthy young volunteers. Therefore, it can be concluded that mizolastine 10 mg could be used safely in elderly out-patients as it preserves functions involved in activities of daily living.