240 patients with mild to moderate knee osteroarthritis were randomized to receive either intra-articular hyaluronan (HA) or placebo injections. The purpose of this study was to investigate the efficacy and tolerability of 5 weekly hyaluronan (HA) injections in patients with knee osteoarthritis (OA). The results of this study found HA injections to be successful in reducing pain and improving function, as assessed via the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Results demonstrated significantly lower scores of pain and stiffness on average over the course of the 18 week study period in patients treated with HA versus placebo, though average WOMAC function scores over the study period did not reach statistical significant difference. Incidence and severity of adverse events were similar between groups.