Obstructıve sleep apnea syndrome is a clinical syndrome characterized by recurrent partial or total obstruction of the upper respiratory tract. The main symptoms are snoring, excessive daytime sleepiness and witnessed apnea. It is a disease that affects 3% to 7% of the middle-aged population. Studies and meta-analyzes have shown that cardiovascular diseases are more common in patients with obstructıve sleep apnea syndrome. Comorbid conditions such as obesity, metabolic syndrome and smoking are higher in obstructıve sleep apnea syndrome patients than in the general population. In addition, hypoxia-reperfusion injury due to intermittent oxygen desaturation occurring in obstructıve sleep apnea syndrome patients, endothelial dysfunction, increased sympathetic system activity, platelet activation, monocyte increase, which play the main role in arteriosclerosis, decreased and increased low-density lipoprotein cholesterol may also be the reason for the frequent occurrence of cardiovascular diseases. The development of cardiovascular disease in obstructıve sleep apnea syndrome patients is an important cause of morbidity and mortality. Evaluating white blood cell neutrophil/lymphocyte ratio, platelet/lymphocyte ratio, lymphocyte/monocyte ratio, hematocrit, platelet distribution width, red cell distribution width, C-reactive protein, and monocyte/high-density lipoprotein cholesterol ratio in the follow-up of obstructıve sleep apnea syndrome patients may be helpful in predicting the development of cardiovascular diseases. Whether obstructıve sleep apnea syndrome patients have metabolic syndrome or smoking should be questioned. Obstructıve sleep apnea syndrome, obesity, smoking and depression are increasingly prevalent diseases worldwide, leading to significant mortality and morbidity. Therefore, multicentre studies involving different societies are needed.