The report deals with the predictive value of a procedure for lifetime detection of tumor in experimental animals. The database included the results of regular cAMP/cHMP tests carried out in 54 rats with radionuclide-inducted tumors and 24 tumor-free rats. The data were processes by statistical methods and the informative value was determined on the basis of standard recommendations. The test was shown to have high sensitivity (85.2%), sufficient predictive value (73%) and diagnostic effectiveness (68%). Application of the test in groups of humans at high risk of tumor development is discussed.