ABSTRACT The study of Colombian agaricobiota is relatively recent. The training of new researchers has allowed more taxonomic surveys, increasing the literature on the subject and indicating the relevance of ecological and conservation studies. During a field survey conducted in the oak forests (Quercus humboldtii) in the Madre Monte Nature Reserve, municipality of Arcabuco - Colombia, in October 2018, about 40 specimens of Agaricales mushrooms were collected. The species were identified following the usual methods in Agaricology of the Laboratorio del Grupo de Investigación Biología para la Conservación de la Universidad Pedagogica y Tecnológica de Colombia. We identified a few species: Campanella elongatispora Singer, Cheimonophyllum candidissimum (Berk. and Curt.) Singer, Marasmiellus bolivarianus Singer, and Pluteus chrysophlebius (Berk. and Curt.) Sacc., which were added as new citations to Colombia. An increase in the area of occurrence of certain species of Agaricales-mushrooms was also reported.