In the last decades, the physiological and pharmacological properties of dopamine receptors were controversial principally because of the lack of selective ligand for some receptor subtypes. Since 1997, some specific D4 agonists have been described and have allowed a therapeutic approach. We report here, compounds described as D4 agonist and when available the SAR. The major studies for physiological implications and their potential biological applications are also reported and principally their interest in erectile dysfunction.