1. The effects of fengabine were compared with those of amitriptyline in healthy elderly volunteers. Doses were administered double-blind and assessments were made before and after ingestion. 2. Psychomotor performance and cognitive ability were measured using tests of choice reaction time, tracking, critical flicker fusion threshold, memory scanning and word recognition. Subjective feelings were assessed using the Leeds sleep evaluation questionnaire (LSEQ) and line analogue rating scales (LARS). 3. Pharmacokinetic data suggest that fengabine may induce its own metabolism following repeated dosing. 4. The findings of this study show that fengabine 200 mg and 400 mg does not produce any noticeable behavioural toxicity in elderly volunteers, in contrast to amitriptyline which had a disruptive effect throughout.