Haemophilia A and B has been associated with increased prevalence of low bone mass (67-86%). The aim of this study was to estimate the prevalence of bone disease in haemophiliacs and its association with potential risk factors. Adult patients with haemophilia A and B followed-up in the Haemophilia Centre of Northern Greece were included. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA) in lumbar spine (LS), femoral neck (FN), total hip (TH) and great trochanter (GT). One-hundred four male patients (aged 45.8 ± 15.1 years) and 50 controls (aged 44.9 ± 12.8 years) were screened. Low BMD was diagnosed in 28 patients (26.9%) and 10 controls (20%) (p=0.0001). Patients had lower BMD in TH (p=0.007), FN (p=0.029) and GT (p=0.008) than controls, without differences in LS. BMD was positively associated with the severity of haemophilia, history of herpes virus C or human immunodeficiency virus and level of physical activity, and negatively with the level of arthropathy. In multiple-regression analysis, only the level of physical activity and 25-hydroxyvitamin D [25(OH)D] significantly predicted BMD. Half of the patients had vitamin D deficiency. In conclusion, our study showed increased prevalence of low BMD in haemophiliacs. The levels of physical activity and 25(OH)D independently predicted low BMD.