The endogenous competitive nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA) is an emerging risk marker for future cardiovascular events. Elevated ADMA concentrations have been described in patients with an adverse cardiovascular risk profile. Recently, various studies investigated the independent role of ADMA as a cardiovascular risk predictor in several patient cohorts. In addition, ADMA might not only be a risk marker but also a causative factor for cardiovascular disease. This review summarizes the literature on the relationship between ADMA, cardiovascular disease and diabetes.