Few studies on the benign joint hypermobility syndrome suggest a tendency toward osteopenia, but there are conflicting results. We assessed bone mineral density in pre-menopausal women with hypermobility. Twenty-five consecutive Caucasian women diagnosed with benign hypermobility syndrome by Beighton score and 23 age- and sex-matched controls were included in the study. Age, menarch age, number of pregnancies, duration of lactation, physical activity and calcium intake were questioned according to European Vertebral Osteoporosis Study Group (EVOS) form. All subjects were pre-menopausal and none of them were on treatment with any drugs effecting bone metabolism or had any other systemic disease. No statistically significant difference was found for body mass index, menarch age, number of pregnancies, duration of lactation, calcium intake, calcium score and physical activity score between the two groups. Total femoral and trochanteric bone mineral density and t and z scores were significantly lower in hypermobile patients compared to the control group. Ward's triangle and femoral neck z scores were also found to be significantly low in hypermobile patients (p < 0.05). Significant negative correlations were found between the Beighton scores and trochanteric BMD, t and z scores (r=-0.29, r=-0.30, and r=-0.32) in hypermobility patients. Low bone mass was more frequently found among subjects with hypermobility (p=0.03). Hypermobility was found to increase the risk for low bone mass by 1.8 times (95% confidence interval 1.01-3.38). Our study suggests that pre-menopausal women with joint hypermobility have lower bone mineral density when compared to the controls and hypermobility increases the risk for low bone mass.