Summary Sickle cell disease (SCD) leads to many complications including osteoporosis and osteopenia. We studied the prevalence and predisposing factors of low bone mass density (BMD) in adults with SCD. In this retrospective study, dual X‐ray absorptiometry bone scans were used to determine BMD in the lumbar spine, femoral neck and ultra distal radius of 103 patients (73 females, 30 males, aged 15–80 years). Chart reviews and a patient questionnaire were used to collect patient characteristics, disease course and severity, and low BMD risk factors. The 79·6% of patients (mean age 36·5 ± 12·5 years) had an abnormal BMD, with a predilection for the lumbar spine (P = 0·001). Analysis by 3 (low BMD versus very low BMD versus normal) or by 2 groups (abnormal versus normal) showed that abnormal BMD was associated with lower body mass index (BMI) (P = 0·003), lower Hb level (P = 0·001) and higher ferritin (P = 0·003). Low BMD patients were more likely to be SS, SC or Sβ0thal than Sβ+thal (P = 0·022). Abnormal BMD was not related to age, sex, menarche, SCD complications, number of crises, iron overload, treatment with hydroxycarbamide or desferal, renal disease, smoking or alcohol. Patients treated with hydroxycarbamide for at least 6 months were more likely to have an abnormal BMD. In this SCD population, abnormal BMD seemed to be independent of sex, age and menopause, whereas BMI, ferritin level, Hb type and level appeared to play a major role.