Abstract: BACKGROUND AND AIM: Combining Hydroxycarbamide (hydroxyurea) therapy and L-Carnitine (HU+LC) was proved effective and tolerable in patients with thalassemia intermedia; however, its role in sickle cell anemia (SCA) was not investigated. This study aimed to assess various aspects of treatment with HU + LC in adult patients with severe forms of SCA. PATIENTS AND METHODS: Ninety‑one adult SCA patients were recruited, then distributed into four treatment groups: Group 1 – 37 patients treated with HU + LC; Group 2 – 16 patients treated with HU; Group 3 – 18 patients treated with LC; and Group 4 – 20 patients received supportive treatment only. Their baseline data were recorded then reassessed 8–12 weeks later. Their compliance was assessed subjectively. RESULTS: Patients were nearly matched as regards gender, age, baseline hematologic, and biochemical data. Compared to baseline, HU + LC treatment significantly increased hemoglobin and reduced reticulocytes, white blood cells, mean corpuscular hemoglobin concentration, and lactate dehydrogenase (LDH). Compared with other lines, HU + LC significantly reduced number of painful episodes, blood transfusions, and in hospital days per year. Adding LC to HU improved patient compliance, with mild side effects. Residence, side effects, baseline hemoglobin (Hb), and Hb F% affected patients’ compliance. Both gender and age did not show any influence on response to treatment while side effects, compliance, baseline Hb, and LDH displayed a significant effect. CONCLUSION: Combining LC with HU for the treatment of adult SCA patients showed superior hematologic and clinical effectiveness. The response was more obvious in severe cases. However, health education about the combination is needed to improve patients’ compliance and therapeutic responses. Trial registration: Clinical Trials.gov, NCT05081349. https://clinicaltrials.gov/ct2/show/NCT05081349. Keywords: Hydroxycarbamide, L‑carnitine, sickle cell anemia, severe forms