Erectile dysfunction is defined by the National Institutes of Health as the inability to attain and/or maintain penile erection sufficient for satisfactory sexual performance. The aim of the study was to test the penile length and girth before and after malleable penile prosthesis implantation, to prove if there was actual decrease in the penile size or no. 30 patients complaining of erectile dysfunction were enrolled in the study. The patients were < 40 years of age, being involved in a stable relationship for at least one year, complaining of erectile dysfunction for at least the past 6 months, failed medical treatment including phosphodiestrase 5 inhibitors or intracavernosal injections. Our study excluded patients with Peyronie’s disease, Patients who have had radical prostatectomy, Post priapetic erectile dysfunction. Flaccid stretched penile length was recorded. Length was determined from pubis to tip (true length) and from skin surface to tip (visible length). Prior to surgery, penile length and girth was measured after induction of artificial erection. Upon implantation, the maximum girth possible was implanted following maximum dilatation. Measurements were repeated on table, 6 weeks post-operative and 4 weeks after first intercourse. All patients filled in a questionnaire indicating their satisfaction with penile size post-operative. The results showed Visible length was shorter postoperative (whether stretched (5.8% difference) or erect (9.5% difference)) than preoperative visible length, a statistically significant difference. True length, however, showed no statistically significant difference preoperative to postoperative, whether stretched or erect. Postoperative girth was 4.9% less than the preoperative erect girth and 11.6% more than the preoperative stretched girth. On answering the questionnaire; 80% of the patients reported decrease in the penile size (length and girth) postoperatively, 17% reported no length or girth changes while 3% reported increase in the penile size. Conclusion; It is likely that prosthetic erection provided by PPI is not quite as long as a natural erection due to artificial sensation or persistent erection. Clinicians must guard against unrealistic expectations with penile size and patients' and partners' sexual satisfactions. The dissatisfaction with penile size following surgery may not be proportionate to the actual loss in size, indicating a psychological element for dissatisfaction that can be alleviated by preoperative and postoperative counseling.