This chapter describes drug for impotence, which include sildenafil and tadalafil. Erectile dysfunction is the indication of sildenafil. Hypersensitivity and patients concurrently or intermittently using organic nitrates in any form are the contraindications of sildenafil. Headache, flushing, respiratory tract infection, angina pectoris, atrioventricular (AV) block, migraine, syncope, tachycardia, postural hypotension, myocardial infarction (MI), cerebral thrombosis, cardiac arrest, paresthesia, tremor, depression, herpes simplex, skin ulcer, esophagitis, abnormal liver function text (LFT), rectal hemorrhage, hypoglycemic reaction, arthritis, deafness, retinal vascular disease, photosensitivity, accidental fall are the adverse effects of sildenafil.