In this prospective, randomized, double blind, placebo controlled clinical trial, 135 patients with osteoarthritis, who were 40-65 years; applied to institution's orthopaedics outpatient clinic; had grade 1, 2, or 3 primary osteoarthritis diagnosed in last 1 year; and had Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score≥40, and Visual Analogue Scale score≥40,were enrolled. Subjects were randomized (1:1) to placebo (n= 67) or combination (n= 68) arms, in which 550 mg naproxen sodium/30mg codeine phosphate was given orally twice a day for 7 days. Rescue medicine was 500 mg paracetamol (max= 6 tablets/day). Demographic characteristics, medical history, adverse events, VAS and WOMAC scores were collected in study visits performed within 10days.The study was approved by local institutional ethics committee and written informed consents were obtained from all participants.