The determination of blood lipase has been proposed by SEABRA as a method for detecting predisposition to initial or subsequent stages of tuberculosis; normal subjects having high titers (8-12 units), tuberculous patients low ones (5-7), falling to zero in advanced stages of the disease. An assay of the method has been made by the AA. in sera of 238 non tuberculous subjects (419 tests) and 207 tuberculous ones (456 tests) following the technical procedures described by SEABRA. All of them had their Roentgenographies taken at the same day of blood collection. Factors interfering with blood lipase values in tuberculosis are discussed. A relationship between the course of the disease and the serum lipase could not be confirmed. High and low values were found in initial as well as in advanced cases. Our results are in agreement with those recorded in the literature (Figs. I and II). It seems that the general condition, rather than pulmonary lesions are responsible for the blood lipase values. There was no direct relationship between blood lipase titer and severity of pulmonary tuberculosis; however the data presented in this paper do not agree with such correlation, stated by SEABRA, FERNANDES and VICENTE.