This is a correlation validation study wherein the English version of the International Index of Erectile Function-5 (IIEF-5) was adapted into Filipino. Many of the sex-related terms in the questionnaire do not have a direct translation in Filipino which made adaptation difficult. In the pretest, there was no difficulty with comprehension and readability of the Filipino version. Subjects judged it as equivalent to the English IIEF-5. There was a high positive correlation with the English version (r=0.93). After modification by a Review Panel, the final instrument underwent validation in a study which included 64 heterosexual, sexually active male aged 40 years old and above. The mean age of the subjects was 54.7. Content validity was determined by 2 urologists. The translated tool was found to be reliable (coefficient of stability=0.92) and could discriminate subjects with or without ED (validity coefficient=0.95). This study did not document treatment responsiveness and specificity. The questionnaire, however, can be used to screen patients with ED. Prevalence among the sample population was determined and found to be 45.3%.