Introduction:-ED was related to traditional risk factors of coronary artery disease such as metabolic syndrome, dyslipidemia, hypertension, type 2 diabetes, smoking and obesity. Objective:- to evaluate the effect of smoking and body mass index on penile duplex parameters (PSV, EDV, RI, Cavernosal artery diameter before and after injection) in patients with erectile dysfunction. Patients and methods Our study was carried out on one hundred and thirty patients above 40 years and complaining of ED for more than 6 months. Selected patients were divided into 4 groups: Group1 (Non smokers/ Non obese) N=36, Group 2(Non smokers /Obese) N=30, Group 3 (Smokers/Non obese) N=34, Group 4 (Smokers and Obese) N=30. Other risk factors for ED were excluded except dyslipidemia. All patients were subjected to personal history, sexual history, past history of medical disorders or operations, evaluation of erectile function using an abridged IIEF-5. Determination of body mass index (BMI) was performed .Measurements of fasting lipid profile, blood sugar, TT, prolactin, PSA were conducted. Penile hemodynamics was assessed using intracavernosal Injection of 1cc Bimix and penile duplex study. Results:- There was a statistically significant difference between mean value of PSV between group 1 and all other groups on both sides and between group 3&4. Also, our results showed a statistically significant difference between mean value of EDV and RI between group 1 and all other groups on both sides. Concerning cavernosal artery diameter change after ICI, a statistically significant difference between the following groups: 1&4, 3&4 on both sides and between group1&2 at Right side only. In this study there was a statistically significant difference between the study groups regarding patient's response to ICI (p-value 0.000). A significant negative correlation between BMI and total testosterone was detected (p-value 0.001). Regarding mean value of serum testosterone, group2 showed a statistically significant difference from group 1and group 3.Conclusion:- Both smoking and BMI are strong risk factors for ED and affect response to ICI and penile duplex parameters(PSV,EDV,RI). Smoking and BMI together cause more deterioration of penile duplex parameters and response to ICI. The effect of Smoking on EDV and RI was more than BMI. The effect of BMI on PSV, response to ICI and testosterone levels was more than smoking.