A short-term, randomized, double-blind placebo-controlled clinical trial has found no evidence that glucosamine chloride leads to structural improvements in patients with arthritis. Patients with mild-to-moderate chronic pain in one or both knees typical of knee osteoarthritis (n = 201) were assigned to receive a drink containing 1,500 mg glucosamine hydrochloride or placebo daily for 24 weeks. Cartilage damage was then assessed by 3T MRI. Patients in the placebo group showed more improvement in terms of bone marrow lesions than those treated with glucosamine hydrochloride (adjusted OR 0.537; 95% CI 0.291–0.990) and cartilage damage was not decreased in the treated group in comparison with the placebo group (adjusted OR 0.938; 95% CI 0.528–1.666).