Background: The clinical phenotypes of children with sickle cell disease (SCD) are poorly described in many sub-Saharan countries including Nigeria. Objectives: The objective was to highlight various clinical phenotypes of SCD in children and investigate the influence of sociodemographic indices on the development of SCD complications. Methods: We carried out a cross-sectional study of 240 pediatric patients attending the sickle cell clinic and the emergency room in a teaching hospital in South-Western Nigeria over a 12-month period. The clinical phenotypes and severity of the disease were documented, and the influence of sociodemographic variables was investigated. Results: The five leading clinical phenotypes in our patients were significant pain episodes, that is, vaso-occlusive crisis in 159 (66.3%); anemic crisis in 62 (25.8%); severe bacterial infections, 57 (23.8%); acute chest syndrome (ACS), 27 (11.3%) and stroke, 7 (2.9%). Forty-two (33.1%) had a previous history of dactylitis (hand-foot syndrome). Other clinical phenotypes such as avascular necrosis of the femur, 4 (1.7%); nephropathy, 2 (0.8%); priapism, gallstone and chronic leg ulcer, one (0.4%) each, were not commonly seen. More children with a history of asthma had ACS. Furthermore, high steady-state white blood cell count was associated with severe disease. Conclusion: The clinical phenotypes of SCD in children from South-Western Nigeria are highly variable with the disease manifesting very early and about 10% having significant complications. Sociodemographic characteristics appear to have little influence on the development of SCD complications among our patients, but age and low-socioeconomic class are associated with anemic crisis.