Background: The Aldrete's score is used to determine when a patient can safely leave the Post-Anaesthesia Care Unit (PACU) and be transferred to the surgical ward. The Aldrete score is based on the evaluation of vital signs and consciousness. Cognitive functions according to the anaesthetic strategy at the time the patient is judged fit for discharge from the PACU (Aldrete's score ≥ 9) have not been previously studied. The aim of this trial was to assess the cognitive status of inpatients emerging either from desflurane or propofol anaesthesia, at the time of PACU discharge (Aldrete score ≥ 9). Methods: Sixty adult patients scheduled for hip or knee arthroplasty under general anaesthesia were randomly allocated to receive either desflurane or propofol anaesthesia. Patients were evaluated the day before surgery using Digit Symbol Substitution Test (DSST), Stroop Color Test and Verbal Learning Test. After surgery, the Aldrete score was checked every 5 min until reaching a score ≥ 9. At this time, the same battery of cognitive tests was applied. Each test was evaluated separately. Cognitive status was reported using a combined Z score pooling together the results of all 3 cognitive tests. Results: Among the 3 tests, only DSST was significantly reduced at Aldrete Score ≥ 9 in the Desflurane group. Combined Z-scores at Aldrete Score ≥ 9 were (in medians [interquartils]): − 0.2 [− 1.2;+ 0.6] and − 0.4 [− 1.1;+ 0.4] for desflurane and propofol groups respectively (P = 0.62). Cognitive dysfunction at Aldrete score ≥ 9 was observed in 3 patients in the Propofol group and in 2 patients in the Desflurane group) (P = 0.93). Conclusion No difference was observed in cognitive status at Aldrete score ≥ 9 between desflurane and propofol anaesthesia. Although approximately 10% of patients still had cognitive dysfunctions, an Aldrete score ≥ 9 was associated with satisfactory cognitive function recovery in the majority of the patients after lower limb arthroplasty surgery under general anaesthesia.