Sublingual sildenafil causes a satisfactory erection in less time in comparison to oral route in the presence of sexual stimulation and there was reduction in the start of the pharmacological activity with sublingual administration. Our work was aiming to evaluate the potential role of sublingual administration of sildenafil as regard the effective dose, the time of response and subsequently on the patients' satisfaction and its side effects versus the oral route. The response of the patients was evaluated according to IIEF-5, the mean score after oral sildenafil was 18.3±4.9 while it was 19.2±5 after sublingual, 62.2% (28/45)of the patients showed a rapid response of action (within 15-30 min) after sublingual administration and none of the patients showed a rapid response after oral administration (within 30-60 min). The other 37.8% (17/45) of the patients that showed a non rapid response after sublingual, the patients with rapid response to sublingual sildenafil achieved a mean score 19.3±4.9 after oral administration while it was 21.7±3.2 after sublingual administration. 13.3% (6/45) of them refused sublingual administration of sildenafil due to its bitter taste and prefer oral route of sildenafil. 86.6% of the patients were free from any side effects (39/45) after sublingual administration of sildenafil, the side effects were headache 4.4% (2/45) heart burn 4.4% (2/45) and hotness and flushing of the face 4.4% (2/45) and only 1 from oral sildenafil complained from hotness and flushing of the face (1/45), these side effects were minimal and well tolerated.