This report describes a rare case of bicipital tenosynovitis in a Maine coon cat. The cat, a three-and-half-year-old neutered female, presented with chronic weightbearing lameness of the left forelimb. Flexion of the left glenohumeral joint and extension of the left cubital joint were resented, and palpation of the biceps brachii tendon in the bicipital groove elicited pain. A mild incongruity of the joint with mild degenerative changes was seen radiographically. Glenohumeral joint dysplasia was suspected. Ultrasound examination revealed marked thickening of the bicipital tendon and moderate effusion of the left bicipital tendon sheath. Positive contrast radiography of the joint confirmed dilation of the tendon sheath. A tentative diagnosis of bicipital tenosynovitis was made and confirmed on arthrotomy. Surgical removal of osteophytes resulted in the cat being free from pain but a mild lameness recurred six months after surgery.