Atherosclerosis is a chronic inflammatory disease proceeding from an imbalance in lipid metabolism and immune responses. Since leukocytes, especially monocytes and monocyte-derived macrophages, play pivotal roles in the progression of atherosclerosis, it is possible that monocyte count is a beneficial marker for predicting cardiovascular disease (CVD). Many epidemiologic and clinical studies have indicated monocytosis to be an independent predictor of cardiovascular events, both in healthy individuals at baseline and in patients with CVD or with high risk diseases for CVD, such as diabetes, dyslipidemia, hypertension and chronic kidney disease. This relationship has been observed in prospective and retrospective cohort studies, and endures after adjustment for several CVD risk factors. Other indicators utilized monocyte count, such as lymphocyte-to-monocyte ratio, monocyte-to-lymphocyte ratio and monocyte-to-high-density lipoprotein cholesterol ratio, were also independently associated with cardiovascular events and its mortality. In this review, we discussed the clinical utility of the monocyte count as a predictive marker in atherosclerotic diseases.