Bromolysergide (BOL 148) and methysergide (UML 491), 2 mg/kg i.p., and saline were administered to rats 45 min before 1-trial passive-avoidance conditioning followed by electroconvulsive shock (ECS) or sham-ECS. On test session (24 h later), the groups treated with both BOL 148 and UML 491 exhibited clear-cut retention in comparison to saline-ECS rats. All drugged groups, regardless of their submission to ECS, showed somewhat less pronounced consolidation than .**GRAPHIC**. rats. The antiamnestic effect brought about by the 2 drugs was discussed in terms of receptor antagonism against ECS-released brain serotonin; the lower passive-avoidance level observed in treated animals was considered in relation to a possible antipunishment effect of antiserotoninergic treatment.