BACKGROUND : The importance of erectile dysfunction (ED) diagnosis and treatment has been highlighted since the early 2000s. However, nearly 20 years after the first phosphodiesterase 5 inhibitor (PDE5i) was marketed, underdiagnosis and undertreatment of ED in the primary health care setting may still be present. OBJECTIVE : To assess the relative frequency of patients who are medically treated for ED before referral to specialized urology care. The secondary objectives were to evaluate possible reasons for non-treatment prior to referral and other signs of undertreatment, namely cardiovascular risk assessment and antihypertensive treatment. METHODS : 200 male patients referred for ED to specialist urology care by general practitioners were screened after consent between January 2016-December 2018. A full standardized medical and sexual history were taken. Previous medical treatment of ED, namely pharmacologic name and dosages, and cardiovascular risk factors were noted. METHODS : Of the 115 included patients, only 33.9% of patients had already taken PDE5i before referral, and none had taken alprostadil by intracavernous route. RESULTS : The mean patient age was 58.68 ± 10.01 years old. Only 45.2% had been prescribed the highest dose of PD5i. From the remaining untreated patients, only 19.7% had ≥3 cardiovascular risk factors, including 5.6% of patients who also presented moderate-to-severe stable or unstable angina requiring a stress test or cardiology assessment before treatment. Regarding the 54 patients with medical history of arterial hypertension, 43.4% and 30.2% were treated for hypertension with a diuretic and a beta blocker, respectively. CONCLUSIONS : More focus on the primary healthcare continuous medical education regarding sexual dysfunction, namely ED, is needed because major undertreatment of ED is still present because low prescription of PD5i before referral is noted. Morgado A, Moura ML, Dinis P, et al. Misdiagnosis And Undertreatment Of Erectile Dysfunction In The Portuguese Primary Health Care. Sex Med 2019;7:177-183.