© 2016 Foundation of Rehabilitation Information.Objective: Early degeneration of the knees might occur in patients with multiple sclerosis secondary to balance and walking impairment and muscle weakness. The aims of this study were to evaluate the knee joints of patients with multiple sclerosis compared with healthy controls, using ultrasonography, and to investigate whether there is any correlation between femoral cartilage degeneration and disease-related parameters. Design: Study participants were 79 patients with multiple sclerosis and 60 healthy controls. The disease-related parameters, Expanded Disability Status Scale (EDSS), Western Ontario and McMaster Universities (WOMAC) osteoarthritis index, visual analogue scale (VAS) for pain severity, and Berg Balance Scale (BBS) scores were recorded. Femoral cartilage and knee effusion were evaluated using ultrasonography. Results: Femoral cartilages of patients with multiple sclerosis were more degenerated than those of healthy controls. Moreover, patients with multiple sclerosis had more effusion in their knees than did controls. In the multiple sclerosis group there was no correlation between cartilage degeneration grade, amount of effusion, and VAS-pain, BBS, WOMAC and EDSS scores. Conclusion: Patients with multiple sclerosis may have more rapid degeneration of the knee cartilage and increased effusion compared with healthy controls. Ultrasonography is an effective method to detect these changes. However, cartilage degeneration was not found to be associated with diseaserelated parameters in multiple sclerosis.