The risk for erectile dysfunction is closely linked to cardiovascular morbidities such as coronary heart disease, arterial hypertension, hypercholesterolemia, and diabetes. Molecular analysis revealed an association between the genotypes in single base polymorphisms and the risk for these cardiovascular morbidities. In this review the current knowledge of association studies of single nucleotide polymorphisms and erectile dysfunction and the response to the PDE-5 inhibitor sildenafil is described.