The aim of the present study is the definition of a brief structured interview (SI) providing scores useful for identification and quantification of pathogenetic factors of erectile dysfunction (ED). A SI was developed and applied to a consecutive series of 320 ED patients. A 13-item SI, with three-factor analysis-derived scales, was identified and applied for validation to an independent consecutive series of 194 ED patients. PGE(1) (10 microg) intracavernosal injection, penile duplex ultrasound (PDU), blood hormones, PSA, glycemia, and lipids were used for the assessment of an organic component (OC), and Middlesex Hospital Questionnaire (MHQ) modified for psychological disturbances. Scale 1, dealing with OC, showed a positive correlation with age, BMI, blood pressure, glycemia, and inverse correlation, with testosterone, PGE(1) and several parameters derived from PDU. Scale 2, related to partner's relationship, was not correlated with organic parameters. Scale 3, which measures psychopathological traits was correlated with MHQ scales. Scale 1 (>3) had a sensitivity of 67.9% and a specificity of 67.6% for OC. SIEDY((c)) provides information on ED pathogenesis and might assist physicians in diagnostic and therapeutic choices.