OBJECTIVES: To assess the cost-effectiveness of the new transdermal therapeutic system (TTS) of fentanyl and subcutaneous injections (SIs) of morphine hydrochloride in the treatment of chronic pain and predict potential budget impact of the implementation of fentanyl TTS in routine clinical practice. METHODS: The pharmacoeconomic model was developed based on the results of Russian observational study, included 45 patients with terminal cancer: 25 patients received fentanyl TTS and 20 – SIs of morphine. At the first stage, the cost-effectiveness ratios (CERs) of therapies during the first month was measured as total costs of medicines and expenses for ambulance services for acute pain relief per one patient without side-effects. At the second stage, the CERs of therapies during subsequent three months was measured as costs of medicines per one unit of pain intensity (PI) reduction (visual pain scale). RESULTS: During the first month of therapy the frequency of ambulance use was significantly lower in patients received fentanyl TTS (0.32 vs 1.05 per one patient per week in the morphine group), this was reflected in lower total costs (12 611, 42 RUB and 23,037.54 RUB per one patient, respectively). Patients in the fentanyl TTS group were less likely to have side effects. The estimated CERs for fentanyl TTS and SIs of morphine were 13,001.46 RUB and 27,756.07 RUB per one patient without vomiting and 23,354.47 RUB and 82,276.93 RUB per one patient without constipation, respectively. Long-term treatment with fentanyl TTS was resulted in decreased PI as compared to SIs of morphine. The three-month CERs were 4,897.05 RUB and 7,869.30 RUB per one unit of PI reduction, respectively. CONCLUSIONS: The present study has demonstrated that administration of new transdermal therapeutic system of fentanyl has the better cost-effectiveness profile in the treatment of Russian cancer patients.