The Authors have tested serum levels of CEA, ferritin, Alpha-1-antitrypsin, parathyroid hormone (PTH) and calcitonin (CT) in 286 patients affected by lung, gastrointestinal, breast and other kinds of cancer and by non neoplastic diseases. 50 healthy subjects were tested as matched controls too. None of the tested patients was subjected to blood transfusion, therapy with iron, radio- or chemotherapy before the blood drawing. Cea, ferritin, PTH and CT were tested by radioimmunoassay; AAT by laser nephelometry. All the healthy subjects showed serum levels of the markers in the normal ranges. Also the percent of cases with contemporaneous pathological markers was examined. The obtained data have been statistically controlled with "chi square" test. The results show that CEA, ferritin, AAT and CT are higher in the tumor groups than in the others. On the contrary PTH seems to be not useful as tumor marker. The Authors conclude affirming that it is not possible to use any of the tested substances as a specific tumor marker but it is useful to test at the same time these markers in the patients suspected to be affected by cancer for an early diagnosis and therapy, as there are few false positive and false negative cases.