[en] The suspicion metals presence in the Piratininga Lagoon ecosystem that is subject to the several environmental contaminations (urban and industrial garbage) has been provoking preoccupation on the population that uses the resources of this lagoon like survival form. The district public government has been interested to verify the contamination conditions for heavy metals in this lagoon. The heavy metals are one of the environmental pollution more noxious forms, because they aren't degradable and can carry to an ecological phenomenon of its accumulation in the substances of food chain. It occurs by the individuals' contamination and accumulation by the consumption of others animal and already contaminated plants. In general, in the final of this food chain is the man. The x-ray fluorescence technique allows result quali-quantitative based in the wavelength measure or in the energies and intensities of the characteristic x- rays emitted by the elements that constitute the sample. It can obtain the information about important chemical elements in the environmental contamination, among them Cr, Ni and Pb. The equipment that we are using is an experimental setup with a x- rays tube of 30 kV and 1 mA, a Si(Li) detector, data acquisition and analysis microcomputer and programs. The results of analysis had shown some traces of contaminations with Br, Pb, Ni and Cr in the water, plants and sediments samples