PurposeRemimazolam, a newly developed ultra-short-acting benzodiazepine, provides early recovery of consciousness but its effects on memory recovery are unclear. This study examined memory recovery after emergence from general anesthesia using remimazolam.MethodsSeventy-four patients undergoing breast surgery between October 2021 and March 2022 were enrolled and randomly assigned to receive propofol (control group) or remimazolam as general anesthetic during surgery. The primary endpoint was the number of posters patients remembered 24 h after surgery (among four posters shown after recovering from anesthesia) as an assessment of memory retention. The secondary endpoints were the recall of a numeric character patients had been shown just before anesthetic induction, as an assessment of retrograde amnesia 24 h after surgery.ResultsSixty-six patients (propofol, 32; remimazolam, 34) were assessed. Patients in the remimazolam group remembered significantly fewer posters shown to them after surgery than those in the propofol group (0 [0 − 2] vs. 2 [1 − 3],p< 0.001). In the remimazolam group, the patients who received flumazenil remembered a higher number of posters than those who did not receive flumazenil (3 [1 − 4] vs. 0 [0 − 0],p< 0.001). All patients remembered all events that occurred during the preoperative period as well as the numeric character.ConclusionPatients recovering from remimazolam anesthesia without receiving flumazenil do not remember events after regaining consciousness.IRBKyushu University School of Medicine Hospital Institutional Review Board (IRB) (approval number: 20212006).Trial registrationThis clinical trial was registered with the University Hospital Medical Information Network (UMIN) Center on September 28, 2021 (UMIN-CTR: UMIN000045593).Implication statementMemory recovery is slower following emergence from remimazolam than from propofol anesthesia.Supplementary InformationThe online version contains supplementary material available at 10.1186/s40981-023-00635-7.