Factors that influenced the choice of dose of oral transmucosal fentanyl at the time of burns dressing change were investigated in a prospective study. After Ethics committee approval, data was analysed from 29 consecutive patients who had been recruited and consented for a study of pain associated with burns dressings. Patients had completed an 11-point verbal pain intensity score (VRS) prior to and after the dressing change. Analgesic use during for this period was documented. Doses of 600 to 1200 mcg of transmucosal fentanyl (Actiq) were given based on individual assessment. The pre-dressing VRS (median [range]) in the 15 patients who received 600 mcg was 8 [3-10] and was higher than the VRS of 6 [2-9] in the 800-1200 mcg group. The time since the burn was longer in the low dose group at 7 [1-22] days compared with 5 [0-50] days in the higher dose group. In addition 73% of the low dose group was prescribed opioids regularly prior to the dressing compared with 57% of the high dose group. The choice of a lower transmucosal fentanyl dose was based on prior use of opioids and the age of the burn rather than on the patient's pain intensity.