OBJECTIVES: To evaluate the cost-effectiveness of celecoxib compared with loxoprofen for the treatment of patients with chronic pain caused by osteoarthritis, rheumatoid arthritis and low back pain in Japan. METHODS: Using the Markov model, long-term simulations were conducted with a 3-month Markov cycle for each regimen of celecoxib vs. loxoprofen in the perspective of Japanese healthcare payers. The direct medical costs and quality-adjusted life years (QALYs) were estimated as outcome measures throughout the lifetime of patients. The base case population was aged 57 years which was the weighted mean age from the cited literature. All the costs were expressed as of March 2014, and annual discount rates of 2% were applied for both costs and health benefits. RESULTS: The incremental effectiveness of celecoxib compared with loxoprofen was 0.024 QALY while the incremental cost was JPY 73,785 (USD 716, USD 1 = JPY 103), indicating the incremental cost-effectiveness ratio (ICER) was JPY 3,131,480 (USD 30,403) per QALY gained. Sensitivity analyses identified two factors substantially sensitive to ICER: 1) decrease in efficacy of celecoxib in the recurrence of symptomatic ulcer, and 2) increase in utility of the primary disease that causes chronic pain while the administration of the drug halts. The literature review, however, supported that both of those sensitive cases are not so much likely to happen. CONCLUSIONS: Celecoxib was considered cost-effective compared with loxoprofen in patients with chronic pain in Japan.