Background: Carcinoembryonic antigen (CEA) is a glycoprotein, which is present in the foetal colon, some benign conditions and different malignancies, particularly in colon adenocarcinoma. We focused this study on non-melanoma skin cancer (NMSC). NMSC is a common malignancy and it is an important source of morbidity and death in the world. In this study we evaluated whether CEA level increases in NMSC. Patients and Methods: A total of 566 patients with non-melanoma skin cancer (NMSC) were enrolled; 286 patients with NMSC showed CEA levels above normal values, and 280 showed CEA levels below normal values. Patients with high levels of CEA underwent abdominal ultrasound, gastro endoscopy, colonoscopy, and abdominal CT scans. Results: We studied 566 patients, 286 were positive to CEA and 280 were negative. Of the 286 patients positive to CEA, 132 had basal cell carcinoma (64 patients had an associated cancer) and 154 had squamous cell carcinoma (75 patients were affected by cancer). Of the 280 patients negative to CEA, 130 had basal cell carcinoma (12 were associated with cancer), and 150 had squamous cell carcinoma (18 were associated with cancer). The mean age of the 566 case control subjects were 65–81 years. Of the 10 subjects that were the positive control for CEA, two had cancer. Of the 556 subjects that were the negative control for CEA, three had cancer. Conclusions: In patients that present high serum levels of CEA, we give attention to adenocarcinoma tumour first. The pattern of association may be attributable to bias because the group with NMSC were frequently evaluated than those with no history of NMSC. Our results showed that out of 286 patients that were CEA-positive, 139 had cancer, and of the 280 that were CEA-negative, 30 had cancer. Therefore, 20% of patients do not follow the trend. Other markers should be investigated.