The Guajataca State Forest is located in the northwest region of Puerto Rico in the town of Isabela. The importance of this study is to identify and document the fungi that grow on dead leaves. No previous study on diversity of fungi has been done in the forest. The goal of this research is to study the diversity of fungi associated with the leaf litter. The study was conducted in March, April, July, June, September, October and November of year 2007. Two areas of study (Inclination Surface and Flat Surface) each with two transects of 60 m. Each transect consists of a sub-plots of 1 m ² every 10 m. A total 62 taxa and 2,049 fruiting bodies were collected. Seven (7) of the 62 taxa were identified to species and fifty-five (55) to genus and morfospecies. The genus with the largest number of species was Mycena (14 species). The frequency is dominated by Gloiocephala sp.1 with 96%, followed by Mycena sp.1 with 83%. The species with the largest number of fruiting bodies was Gloiocephala sp.1 with 1,168 fruit bodies to (58%). The study found that of fungi that colonize leaf litter vary according to time and space in the Guajataca State Forest.