Recent literature has suggested the independent contribution of obstructive sleep apnea syndrome (OSAS) to the pathogenesis of metabolic disturbances. The objective of our work was to determine, in a Tunisian population of patients with OSA, the prevalence of metabolic syndrome (MS) and the factors associated with its occurrence. The prevalence of MS was 60%. Compared to apneics without MS, those with MS were older (p=0.001), more obese (p=10-³), had more frequent cardiovascular comorbidities (p=0.001), had more SIB (p=0.04), more lipid and carbohydrate disturbances in untreated patients (p=10-³). We found a significant association between the severity of OSAS and some components of DM: hypertension (p=0.03) and T2DM or high GAD (p=0.05). On multivariate analysis, we noted a positive and statistically significant correlation for only 3 factors: BMI, TG and YAG in untreated patients. SM is common in OSA. Its occurrence is not correlated with the severity of OSAS. Thus, its screening must be systematic to allow an adapted management.