We describe the clinical features of S-C hemoglobin disease in 106 adults seen during the years 1972-2000 and followed for a mean period of 6.8 years (range 1-27 years). The median age of the patients was 50 years. Common clinical features were pain crisis (65%), avascular necrosis of the hip (23%), proliferative sickle retinopathy (34%), and splenic infarction/splenic sequestration syndrome (19%). Acute splenic sequestration crisis occurred in 10 patients and was the presenting feature in two. Obesity (19.8%), essential hypertension (20.7%), and type-2 diabetes mellitus (10.3%) were common. The frequent occurrence of these co-morbidities among patients with hemoglobin S-C disease has not been reported previously. Copyright 2001 Wiley-Liss, Inc.