We describe a patient with Fabry's disease who for many years was seen in other clinics and was thought to have an undifferentiated connective tissue disease or an incomplete form of CREST syndrome. He presented with polyarthralgias; multiple telangiectasia-like lesions in his oral mucosa, hands, and periumbilical area; mild dysphagia; Raynaud's phenomenon; bilateral leg lymphedema; renal insufficiency; and aseptic bone necrosis at both knees. The diagnosis of Fabry's disease was first suspected when ultrastructural studies on his kidney revealed the typical inclusions characteristic of glycosphingolipidosis. Diagnosis of Fabry's disease was later confirmed by finding similar inclusions in skin endothelial cells and demonstrating a low alpha-galactosidase A activity in plasma. Fabry's disease, although rare, must be considered in the differential diagnosis of patients considered to have "atypical undifferentiated connective tissue diseases," even in the absence of classic angiokeratomas.