The aim of the investigation was to find whether a single dose of ACTH4-10 could alleviate the retrograde dysmnesic effects of unilateral ECT and improve retrieval. Twenty depressive inpatients participated in the study, which was a double-blind intraindividual cross-over comparison between ACTH4-10 (30 mg subcutaneously) and placebo. The drug was administered 150 min after learning and 90 min after the second or third ECT unilateral treatment. Retrieval was tested 30 min after the administration of the drug. An identical design was used in 20 unmedicated healthy female subjects. The results of both studies give no support to the hypothesis that a single dose of ACTH4-10 facilitates memory retrieval.