Summary Erectile dysfunction (ED) is the most common male sexual problem worldwide. The association between ED and components of metabolic syndrome (MtS) is well established. This study examined neck circumference (NC) as a possible indicator of MtS and also of ED. Ninety‐two patients were included and divided into two groups. Group 1 consisted of 47 patients with ED and Group 2 consisted of 45 healthy volunteers. Questionnaires, differences in anthropometric and laboratory measurements between patients with ED and the control group, and a cut‐off value for NC were investigated. The mean NC in ED patients was higher in Group 1 than in Group 2 (P = 0.001), and Group 1 also demonstrated more MtS criteria than Group 2 (P < 0.001). The cut‐off point of NC was defined as 34.75 cm for ED and MtS. The cut‐off values of waist circumference for ED and MtS were 105.5 and 102.5 cm respectively. In the light of these findings, NC may be a new component of MtS in ED patients. Additionally, NC may be a novel indicator of central obesity and ED. We suggest that NC values of 35 cm and over may predict ED in patients with MtS.