Diplazium errans and Polystichum schizophyllum, endemic to the state of Guerrero, Mexico, are described and illustrated. The former is distinct by its long lanceolate once-pinnate leaves with numerous pinna-pairs and the presence of rhizogenous buds on the rachis toward the blade tip. The latter is distinguished by its tripinnate blades, persistent light-tan indusia, and by marginate, most often black-tipped scales on the stipe and rachis. The relationships of these spe- cies within the corresponding genera and especially to their Mexican congeners is discussed. RESUMEN.-Se describen e ilustran Diplazium errans y Polystichum schizophyllum, especies en- d6micas del Estado de Guerrero. La primera se distingue por sus largas hojas lanceoladas una vez pinnadas con numerosos pares de pinnas y la presencia de yemas rizogenas en la parte terminal del raquis. La segunda se reconoce por sus hojas tripinnadas, indusios persistentes de color pardo claro y la presencia con frecuencia de escamas marginadas con puntas negras en el peciolo y raquis. Se comentan ademas las relaciones de estas especies con otras de los g6neros correspon- dientes, en particular con sus congeneres mexicanos. In the early 1980s, the state of Guerrero in southern Mexico was targeted as one of the regions for which floristic knowledge was poor. For the last fifteen years, different Mexican research institutions have collected extensively in the state in order to amass collections sufficient to publish a proper floristic account. Part of the outcome of these years of field work has been the discovery of several new plant species. Here we name two of the previously undescribed ferns. Ferns in Mexico are fairly well known, although relatively few fern floras