Objective: This study aimed to document the transition of hemoglobin (Hb) F levels from early childhood to adulthood in Kuwaiti sickle cell disease patients, investigating its relationship to sex, Hb genotype and coexistence of α-thalassemia trait. Subjects and Methods: The following parameters were extracted from the patients’ records: age, sex, Hb, mean corpuscular volume, mean corpuscular Hb, red blood cell count, Hb F, Hb S, Hb A₂ and α-globin genotype. Hb quantitation was performed with cation exchange HPLC, while α-globin genotype was determined by PCR. Results: Records were available for 149 patients, made up of 94 SS and 55 Sβ⁰thal; 83 males and 66 females, aged 3 months to 60 years (mean 10.5 ± 1.8). The mean Hb F level in the whole population was 21.5 ± 8.1% and was not significantly different between males and females, and SS or Sβ⁰thal. When the age groups were analyzed, the Hb F level was highest (28.9 ± 10.9%) in those below 5 years. Indeed, patients ≤2 years had a mean level of 31.9 ± 13.0%. There was no significant difference in the Hb F levels in SS patients with or without coexistent α-thal trait. Conclusions: Kuwaiti sickle cell disease patients below 5 years of age have close to 30% Hb F and this is probably a major reason why they usually do not present before this age, unlike patients elsewhere who present within the first year of life.