Ochronosis is the musculoskeletal manifestation of alcaptonuria, a rare autosomal recessive disorder with an estimated prevalence of below 1:250 000.1 Alcaptonuria is associated with deficient homogentisate 1,2-dioxygenase (HGO) activity in the liver,2 causing production of large quantities of homogentisic acid (HGA). In urine and tissues, HGA oxidises to benzoquinones, which in turn form melanin-like polymers. Tendons are sites of ochronotic pigment deposition because of their high collagen content.3 Several cases of tendon and ligament ruptures in alcaptonuria have been reported.1 4 5 To our knowledge, no studies have been carried out regarding tendon pathology in ochronosis. Ultrasonography (US) is an inexpensive, repeatable, non-invasive exam that permits accurate visualisation of tendons and ligaments. Our …