The pursuit of the ideal tumor marker has generated many tests for use in the diagnosis and management of cancer, several of which are now widely available. The objective of this study was to evaluate the diagnostic utility as a cancer marker of plasmatic levels of ceruloplasmin. Ceruloplasmin is a glucoprotein that transports serum copper. A case-control design was used. Serum values were evaluated in 144 patients and 103 normal controls by receiver operating characteristic (ROC) curve analysis to define the optimal cut-off levels for the serum values of ceruloplasmin in the diagnosis of cancer. The ROC analysis showed that ceruloplasmin is considerably sensitive in men (80%) at the specificity level of 80.3% and in women the sensitivity (Se) was (63.2%) and the specificity (Sp) was (63.3%). According to this study, it would seem optimal to use the cut-off level of 358 mg/l in men and 383 mg/l in women. In conclusion, serum ceruloplasmin was significantly elevated in advanced stages of solid malignant tumors, however, locally advanced or locoregionally spreading tumors did lead to significant increases (P < 0.01). Finally, the results of ROC curve analysis suggest that the ceruloplasmin is characteristic of good diagnostic markers.