Erectile dysfunction (ED) is a complex neurovascular phenomenon under hormonal and psychological control, it includes arterial dilatation, trabecular smooth muscle relaxation and activation of the corporal veno-occlusive mechanisms. This study was designed to evaluate the role of color Doppler ultrasound following cavernosal injection of Alprostadil 20µg in assessment of borderline arterial peak systolic velocity (PSV) in patients suffering from diabetes mellitus in order to assess the response to oral vardenafil 20 mg. These data were collected from patients attended Al-Shaheed Ghazi Al-Hariri Teaching Hospital from December/2016 until June/2017. Penile doppler ultrasounds were performed after intracavernosal injection of 20µg Alprostadil in diabetic patients, examination done at (Time 0, 5, 10, 15 and 20 minutes) with injection given at zero time, and maximum velocity was taken at each of the above times but the most important velocity was at time of 20 minutes to give the final result. The patients with borderline PSV reading (25-35cm/sec) were given 20mg vardenafil orally and responding was assessed by patients' ability to gain satisfactory erection and penetration. Chi-square test with statistical significance of p-value<0.05 was used. The current study included (50) male diabetic patients with erectile dysfunction (determined by inability to gain satisfactory penetration). There are 30 (60%) patients aged from 50 to 69 years and 20 (40%) patients aged between 30 and 49 years. Of those 9(45%) patients had responded to vardenafil. There were 17(34%) patients with type I diabetes mellitus, only 4(23%) patients of them responded to vardenafil, while 10(30%) out of 33(66%) patients with type II diabetes mellitus (DM) had response to vardenafil. There were 10(41.7%) with PSV ranging from 30-34.9 cm/sec had responded to vardenafil whereas only 4(15.3%) with PSV ranging from 25 – 29.9 cm/sec had responded to vardenafil. Ultrasound with doppler study for penile artery with 20 mg injection of Alprostadil was considered a valuable approach for diagnosing arteriogenic ED. Moreover, PSV has shown a key role in diagnosing, treatment and follow up arteriogenic ED.