Our aim is to evaluate circulating CD34 as a novel predictive marker of occurrence of vascular event in Children with Sickle Cell Disease in their steady state and relate levels to severity of VEs in the following 6 months.Patient and Methods: This study was an exploratory study, conducted at Pediatrics Hematology-Oncology Unit at Ain Shams University Children's Hospital, where 50 children with sickle cell disease were enrolled at their steady state (defined as 2 months free from any Vascular Event prior to the study), aged 6 months - 16 years. Flow cytometry was done for quantification of circulating CD34+ at inclusion and compared to age and sex matched control and patients were followed up for 6 months for vascular events. Results: There is statistically significant higher level of CD34+ among SCD patients compared to age and sex matched control with p value