Vinpocetine (CavintonB), vincamine, and nicergoline (SermionB) were evaluated for the ability to protect cognitive function of spontaneously hypertensive rats from the damaging effect of hypoxia. Normobaric hypoxia (6% oxygen) was applied during the acquisition of a two-way active avoidance task (3 sessions, 50 trialsisession). Hypoxia decreased the percentage of conditioned avoidance responses by 50% on day 3. Vinpocetine (1.25-1 0 mg/kg) administered orally 60 min prior to the daily sessions did not significantly improve learning in normoxic conditions; however, it prevented hypoxia-induced learning deficit (1.25 mg/kg peak effect dose). The dose-response relationship for the compound is an inverted U-shaped curve. Vincamine (2.5-20 mgikg p.0.) did not facilitate learning under normoxic conditions, but afforded protection against hypoxia at the 20-mgikg dose. Nicergoline (2.5-20 mg/kg p.0.) did not increase acquisition of the normoxic avoidance response, and it also showed a moderate antihypoxic effect. Vinpocetine, and to a lesser degree vincamine and nicergoline-drugs useful in the therapy of cognitive disturbances following cerebral ischemichypoxic states-proved effective in the prevention of a hypoxia-induced learning deficit.