BACKGROUND: Both steroid and hyaluronic acid (HA) are effective therapeutic regimens when used as intra-articular (IA) injections for knee osteoarthritis. This study was performed to re-estimate the hypothesis that the IA injection of HA is more effective than that of steroid. METHODS: A retrospective study was conducted by reviewing the medical records of osteoarthritis of the knee patients treated only by IA injection with HA or triamcinolone (Triam) at our pain clinic over the last 28 months. The HA group (N = 17) received an IA injection of 25 mg of HA followed by a 5 ml injection of 1% lidocaine once a week for 5 weeks. The triam group (N = 34) received an IA injection of a mixed solution of 5-10 mg of triamcinolone and 6-8 ml of 1% lidocaine 3 to 5 times at one or two week intervals. Pain improvement was compared using pain relief scale (PRS) scores at the end of a series of IA injections in each patient. RESULTS: Both groups showed significant pain improvement following a series of IA injection, compared to the pre-treatment pain state; mean PRS post-injections was 5.1 +/- 2.6 in the HA group and 6.1 +/- 2.9 in the Triam group (P < 0.05 for both). However, there were no significant differences between the groups. CONCLUSIONS: Our results suggest that IA injections with either HA or triamcinolone are effective in knee osteoarthritis. No significant difference was found between Triam and HA use in IA injections for knee osteoarthritis.