The aim of this study was to examine and compare the efficacy and safety of combining strong opioids (transdermal fentanyl) with weak opioids (codeine or tramadol) for the management of severe cancer pain. Forty six patients (25 male / 21 female) aged 42-80 years were studied. According to an eleven-grade numeric rating scale (NRS; 0 = no pain, 10 = severe pain), they all had severe steady pain intensity greater than 5 (NRS >5) despite treatment with weak opioids and adjuvant drugs, as proposed by the 2nd step of the World Health Organization (WHO) analgesic ladder, at the maximum tolerated doses.