Background Sickle cell disease (SCD) is an autosomal recessive hemoglobinopathy that is very common and causes a great burden in Saudi Arabia and worldwide. This study aims to determine the frequency and benefits of using hydroxyurea in treating children with SCD in King Abdulaziz University Hospital (KAUH) in Saudi Arabia. Method This retrospective observational study included all SCD patients, males and females, who were following up in KAUH and were less than 18 years old. Patients on chronic transfusion therapy or who had previous stem cell transplantation were excluded from the study. The study was approved by the unit of biomedical ethics in KAUH, Jeddah. Result The study included 102 SCD patients; the median age of the sample was 7.5 +/- 4.2, with the majority being female (58 patients; 56.9%). Hydroxyurea users among participants in the study were 62 patients (60.8%). Thirty-seven (37) of the patients using hydroxyurea had an increase in the mean corpuscular volume (MCV). There was a decrease in the level of white blood cells (WBCs) and neutrophil count from 15.81 +/- 10.24 and 48.31 +/- 23.23% to 12.48 +/- 5.48 and 40.81 +/- 15.78%, respectively. Platelet count showed an increase from 345.4 +/- 2.1096 to 359.162 +/- 199.87 after starting hydroxyurea. The incidence of vaso-occlusive crisis (VOC) increased after hydroxyurea initiation from 4.555 +/- 4.08 to 6.288 +/- 9.80. Moreover, the frequency of blood transfusion in patients using hydroxyurea was statistically significant as p-value = 0.048. Conclusion In conclusion, our results showed significant clinical and laboratory benefits of hydroxyurea in children with SCD. Hydroxyurea has been shown to reduce the frequency of VOC and blood transfusion in patients with SCD.