Introduction: In the work up of primary solid liver lesions it is essential to differentiate correctly between benign and malignant tumors, such as hepatocellular adenoma (HCA) and hepatocellular carcinoma (HCC) respectively. A promising new marker to detect HCC is Golgi Protein 73 (GP73). Studies comparing patients with HCC and cirrhosis with normal controls suggested that GP73 is specific for patients with HCC; however, patients with other liver tumors were not included. We therefore studied the predictive value of GP73 in differentiating between solid benign and malignant liver tumors. Materials and Methods: This study included 264 patients: 88 patients with HCC, 88 with hepatocellular adenoma (HCA), and 88 with focal nodal hyperplasia (FNH). A blood sample was collected from each patient to measure GP73 levels using a quantitative ELISA assay and differences in outcome between subgroups were compared. The receiver operating characteristic (ROC) curve, sensitivity and specificity of GP73 were calculated and compared to alpha-fetoprotein (AFP) levels. Results: When comparing malignant and benign liver tumors the area under ROC was 0.701 and 0.912 for GP73 and AFP respectively. Test characteristics revealed a sensitivity of 60% for GP73 and 65% for AFP; in addition the specificity was 77% for GP73 and 96% for AFP. Conclusion: Although the literature suggests that GP73 is a valuable serum marker in patients with HCC, the serum concentration may also be increased in patients with solid benign liver tumors. Therefore, a GP73 assay is less suitable for discriminating between primary malignant and benign tumors of the liver.