Adult male Wistar rats were bilaterally implanted with indwelling cannulae in the agranular insular cortex of the prefrontal cortex. After recovery, animals were trained in a step‐down inhibitory avoidance task (3.0‐s, 0.4‐mA footshock) and received, immediately after training, a 0.5‐μl infusion of the serotonergic type 1A (5‐HT1A) receptor agonist dipropylamino‐8‐hydroxy‐1,2,3,4‐tetrahydronaphthalene hydrobromide (8‐OH‐DPAT) or of the 5‐ HT1Areceptor antagonist 1‐(2‐methoxyphenyl)‐4‐[4‐(2‐phthalimido)butyl] piperazine hydrobromide (NAN‐190), or of vehicle alone (20% DMSO). Retention testing was carried out 24 h after training. 8‐OH‐DPAT (1.25 and 6.25 μg but not 0.0125 or 0.125 μg) was amnesic. NAN‐190 was not effective at 0.125 or 1.25 μg any dose but reversed amnesia when given at 1.250 μg simultaneously with both effective doses of 8‐OH‐DPAT. These results show that an overactivation of 5‐HT1Areceptors in the agranular insular cortex impairs memory consolidation of inhibitory avoidance, in rats, immediately after training. This suggests that these receptors of the insular cortex may modulate memory consolidation.