Background: Intra-articular injection is a commonly performed procedure in patients with degenerative osteoarthritis of the knee. Several drugs are used for relief of pain in such cases. Local anesthetics, clonidine and steroids have been confirmed to be effective when used in an intra-articular injection. Ketorolac has recently become one of the most commonly used and potent NSAIDs. There have been many studies about the effect of ketorolac. Methods: Sixty-four patients were divided into 2 groups. In Group I (n = 31), 0.5% bupivacaine 3 ml and sodium hyaluronate 20 mg were used and in Group II (n = 33), 0.5% bupivacaine 3 ml, sodium hyaluronate 20 mg and ketorolac 5 mg were used. We observed the pain relief scale (PRS) at 15 minutes, 1 week and 1-3 months after injection. Results: After 15 minutes, PRS scores were $6.6{pm}2.7$ (Group I) and $5.1{pm}3.1$ (Group II), so there was a statistical difference between the two groups. After 1 week, the PRS scores were $5.9{pm}2.0$ (Group I) and $5.8{pm}2.4$ (Group II). At 1-3 months later, PRS scores were $5.6{pm}3.0$ (Group I) and $5.1{pm}2.7$ (Group II). Thus, there were no significant statistical differences between the two groups at 1 week or 1-3 months later, although some patients were more satisfied with pain relief in Group II at 1-3 months. Conclusions: Ketorolac provides more rapid pain relief of degenerative arthritis when used in intra-articular injection. And there was no statistical difference of effect after 1 week or 1-3 months later. Further studies are required on the effect of the intra-articular use of ketorolac.