IN ORDINARY QUANTITATIVE ELEMENTARY CHEMICAL ANALYSIS BY X-RAY FLUORESCENCE, THE CONCENTRATION OF AN ELEMENT IN A GIVEN SAMPLE, IS DERIVED ON THE BASIS OF THE MEASURED FLUORESCENT INTENSITY EMMITED BY ITS ATOMS. SUCH A PROCEDURE HAS A FUNDAMENTAL DRAWBACK THAT LIMITS ITS APPLICATIONS TO A LARGE EXTENT, NAMELY: THE FACT THAT THE MEASURED INTENSITY IS NOT A FUNCTION (FOR MOST THE CASES) OF THE CONCENTRATION OF THE ELEMENT, BUT IT DEPENDS, TO A HIGH DEGREE, ON THE PROPERTIES OF ABSORPTION, FOR X-RAYS, OF THE WHOLE SAMPLE. A VERY SIMPLE MATHEMATICAL EXPRESSION WHICH HAS BEEN CALLED ”THE ABSOLUTE INTENSITY” IS DERIVED IN THIS PAPER. THE STARTING POINT IS A SIMPLE THEORETICAL FORMULA FOR THE FLUORESCENT INTENSITY WHICH IS MEASURED WITH THE SPECTROGRAPH FOR AN ELEMENT IN A GIVEN SAMPLE. THE ABSOLUTE INTENSITY IS EQUAL TO THE PRODUCT OF THE MEASURED FLUORESCENT INTENSITY BY THE SUM OF TWO ABSORPTION COEFFICIENTS; THESE LATTER CAN BE DETERMINED BY THE SPECTROGRPH ITSELF. A VERY INTERESTING PROPERTY OF THE ABSOLUTE INTENSITY IS DUE THE FACT, THAT A PROPORTIONALITY DOES EXIST, BETWEEN THE CONCENTRATION OF THE ELEMENT IN THE SAMPLE, AND THE ABOVE MENTIONED INTENSITY, AND THAT SUCH A RELATIONSHIP IS PRACTICALLY INDEPENDENT OF THA ABSORPTION PROPERTIES. THIS RESULT HAS BEEN PROVED EXPERIMENTALLY AND THE THEORETICALLY TO BE TRUE; AND IT IS ILLUSTRATED BY APPLYING IT TO SEVERAL QUANTITATIVE DETERMINATIONS OF URANIUM IN SYNTHETIC SAMPLES. THESE ANALYSES GIVE RESULT THAT SIMPLY RELATIVE ERRORS LESS THAN 10 % OF THE VALUES. ANOTHER IMPORTANT FEATURE OF THE ABSOLUTE INTENSITY METHOD IS THAT IT MAY BE APPLIED USING PREVIOUSLY DETERMINED DATA BUT WITHOUT EMPLOYING STANDARD SAMPLES. THE OBTAINED PRECISION IS SIMILAR TO THE ABOVE MENTIONED ONE.