Sclerostin, a glycoprotein involved in vascular calcification, could play a role in cardiovascular disorders. Obstructive sleep apnea (OSA) is frequently associated with cardiovascular comorbidities. Thus, in this study we set out to assess the level of sclerostin in patients with OSA. Sclerostin was evaluated in the serum by ELISA method in 106 patients (43 women) with OSA of the mean age of 55 ± 10 years, BMI of 33.1 ± 7.9 kg/m(2), and apnea/hypopnea index (AHI) of 29.7 ± 18.9. There were 76 (72 %) patients with cardiovascular comorbidities in the OSA group. The results were compared with those in 49 healthy control subjects. We found that the level of sclerostin was higher in the female OSA patients than that in female controls (80.1 ± 36.5 pg/ml vs. 61.4 ± 24.1 pg/ml; p < 0.05) and it correlated with AHI (rs = 0.32, p < 0.01) and desaturation index (rs = 0.34, p < 0.01). Further, in OSA women with cardiovascular comorbidities, sclerostin was higher than in women without such comorbidities (87.0 ± 37.4 pg/ml vs. 57.3 ± 22.1 pg/ml; p < 0.05). In men, there were no differences in the serum sclerostin level between the OSA and control subjects, nor was there any relationship with cardiovascular diseases. In conclusion, increased serum sclerostin coincides with the severity of OSA and its cardiovascular sequelae in female patients.