The bromatological characterization of the Agaricus sylvaticus species (A. sylvaticus), known as the Sun Mushroom and cultivated in Brazil, is necessary to determine substances with pharmacological and nutritional potential, in view its safe use in food and in human medicine. The purpose of the present study was to determine the chemical composition of the A. sylvaticus mushroom grown in Brazil. Mushrooms were obtained in dehydrated form from a producer in Minas Gerais State. Through this study it was able to observe the fungus' rich chemical composition, highlighting the variety and quantity of minerals as well as its high protein content. There are many components of this mushroom that have medicinal properties, which are recognized as excellent antioxidants. Results also proved that the composition of A. sylvaticus presented differences when compared to the chemical composition of other Agaricaceae fungi.