Bedsore and ulcer care can often be painful and no standardized analgesic method exists today for pain relief during treatment in adults and the elderly. To evaluate the analgesic efficacy of a nitrous oxide-oxygen mixture vs. morphine during painful bedsore and ulcer care in adult and elderly patients, we conducted a randomized, crossover, multicenter, prospective, open-label, pilot study. Thirty-four inpatients, aged 53-96 years (median 84 years), were recruited in Grenoble University Hospital, Annecy Hospital and Chamb? Hospital, France, from January to June 2001. Each of the 34 patients received morphine (M), nitrous oxide-oxygen mixture (E), or morphine+nitrous oxide-oxygen mixture (ME) during painful care in a crossover protocol. Treatments were changed every two days and the study duration was six days. Analgesia was evaluated before and after each care session using a behavioral scale to evaluate pain in noncommunicating adults (ECPA), a visual analog scale (VAS), a global hetero-evaluation scale (GHES), and the DOLOPLUS-2 scale. There was a significant overall difference (P<0.01) among the three treatments. On the ECPA, the average difference after and before care was +5.2+/-8.6 (M), -0.3+/-8 (E), and -0.6+/-7.4 (ME), respectively. There was a significant difference between M and E, and M and ME (each P<0.01). No difference was found between E and ME (P=0.97). There were similar significant differences in the GHES and DOLOPLUS-2 scales (all tests P<0.01). Post hoc comparisons showed a significant difference (P<0.01) between M and E, and between M and ME without any additional effect for M+E. No differences were found with regard to safety or tolerability. This pilot study demonstrates the superiority of nitrous oxide-oxygen mixture over morphine for analgesia. This experience suggests that this mixture has ease of use, rapid effect, and limited contraindications when used during painful bedsore and ulcer care in elderly patients. Furthermore, it is well accepted by these patients and by nursing staff.