Patients with sickle cell disease (SCD) suffer from impaired health-related quality of life (HRQoL). This study aimed to determine the level of HRQoL, sense of coherence (SOC), and self-efficacy (SE) in a sample of SCD patients, and to explore predictors of their physical and mental HRQoL. A cross-sectional descriptive study was conducted on 83 SCD patients of one university hospital. The data of the study was collected through Persian versions of the Short-Form Health Survey SF-36 (RAND 36-item), the Sense of Coherence Scale (SOC-13), and the Sickle Cell Self-Efficacy Scale (SCSES). The mean age of the patients was 26.34 ± 8.19 years old. Patients' mean scores for the Physical Component Summary (PCS), Mental Component Summary (MCS), SOC, and SCSES were 40.57 ± 17.18 (range: 0-100), 50.44 ± 17.95 (range: 0-100), 52.40 ± 15.35 (range: 13-91), 26.40 ± 6.96 (range: 9-45), respectively. Regression models showed that the level of the patients' SOC, was the main predictor of the MCS (β = 0.37, p < 0.001). However, the level of the patients' SE was the main predictor of the PCS (β = 0.30, p = 0.004). Also, "blood transfusion history" in patients was a common predictor for both the PCS (β =  - 0.28, p = 0.008) and the MCS (β =  - 0.29, p = 0.003). These results can assist nurses and clinicians to plan clinical interventions for SCD patients by focusing on increasing the level of the SOC and SE and improving SCD patients' HRQoL. Furthermore, measuring the level of the SOC and self-efficacy as screening tests are useful to find patients with a greater risk of impaired HRQoL.