Degraded articular cartilage resulting from osteoarthritis and oxidative stress can affect both humans and animals. Glucosamine (GLN) sulfate is readily absorbed and distributed throughout the body. Glucosamine sulfate has been shown to have anti-inflammatory properties in animal models, regulate mRNA of matrix metalloproteinase1, and support the growth of the proteoglycans in vitro. Additionally, glucosamine sulfate has been shown to reduce induced oxidative stress in vitro. This studys purpose is to determine the effects of oral glucosamine sulfate supplementation on gait parameters and blood oxidative levels in the aged horse. Greater front fetlock dorsi flexion was observed in glucosamine supplemented horses as compared to controls. No differences were observed in plasma thiobarbituric acid reactive substances levels between control and treatment horses. Oral supplementation of glucosamine sulfate resulted in modest changes in biomechanical parameters measured. Differences in blood oxidative levels between treatments were not observed.