This study examined the differences in gait mechanics, isokinetic knee strength, and flexibility between a group of adults with symptomatic osteoarthritis (OA) of the knee (n = 15) and an age-, mass-, and gender-matched group of control subjects (n = 15). Both groups performed under similar environmental conditions. Our results suggest that patients with symptomatic OA of the knee have poorer flexibility in both the affected and unaffected legs and demonstrate significantly less (p less than .05) knee angular velocity and, to a lesser extent, knee range of motion during gait. They have an increased loading rate in the unaffected leg after heel strike, exert less peak vertical force during pushoff, and are significantly weaker in both the dominant and nondominant legs compared to adults with no lower extremity disease.