Metabolic syndrome (MS) comprises a cluster of risk factors for the development of cardiovascular diseases, which are among the leading causes of morbidity and mortality worldwide. Many studies have shown that neck circumference (NC) has validity in the measure of MS since it correlates positively with the traditional components. For these reasons, this study aimed at comparing waist circumference (WC) and NC for identifying MS parameters in patients treated at a cardiology unit. This study included 309 patients assisted in a Cardiology Unit. Biochemical and anthropometric parameters were evaluated. Correlations between neck and WC with anthropometric, biochemical, and atherogenic indices were evaluated. The diagnostic ability of neck and WC was assessed by using the receiver operating characteristics curve. The patients had a mean age of 57.2 years, and 56% were men. The diagnosis of MS was present in 48% of men and 39% of women. Neck and WC showed a positive correlation with each other, and both showed positive correlations with the criteria for MS. Moreover, NC showed a positive correlation with body mass index (BMI), insulin, homeostatic model assessment (HOMA)-β, and C-reactive protein. WC showed a positive correlation with BMI, HOMA of insulin resistance (HOMA-IR), and Castelli Index I. Both neck and WC showed the ability to identify the presence of the MS. Both neck and WC showed a significant correlation with several of the metabolic parameters, including some used as criteria for the diagnosis of MS. In addition, both measures demonstrated a good ability to predict MS, making these measures promising for screening patients with this syndrome.