Located at the west center of Honduras, lake Yojoa, with an area of 89 km2 is an important natural reservoir for drinking water and irrigation. Fishing is also essential for the economy of the local population. The erosion of shores and the imput of the process water from the mine of El Mochito, located near the main river running into the lake, seem to be the reasons of a pollution by heavy metals. From december 1988 to may 1989 four metals were analysed by atomic absortion on 31 samples of sediment and 26 samples of fish. The concentrations observed in the center of the lake looks dangerous for lead (2600mg/g d.w.) and zinc (1800 mg/g d.w.) and hight for copper ( 380 mg/g d.w.) and cadmium ( 18mg/g d.w.). However, the samples of fish analysed did not present higher concentration of these metals. This result suggest that, until now, most of these heavy metals are inmobilized in the sediment.