Pigeons were trained to acquire a new four-response position sequence each day by pecking three response keys in a predetermined order. The key color varied after each correct response prior to food delivery. Acute administration of delta 9-tetrahydrocannabinol (delta 9-THC) up to a dose that completely eliminated responding, had no effect on total acquisition errors, or on within session patterns of error elimination. Chronic administration of delta 9-THC (3-10 mg/kg/day), either before or after the session for 4-7 weeks, also did not affect these error measures, although rates of responding were markedly suppressed and at times no responding occurred. Discontinuation of delta 9-THC administration for periods of 4-6 weeks also was without effect on errors. These experiments suggest that neither acute nor chronic delta 9-THC produce specific effects on the repeated acquisition of serial position responses in pigeons.