Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)We recorded evidence for herbivory in the mosses Hypopterygium tamarisci and Lopidium concinnum in a tropical rainforest (Sao Paulo State, Brazil). We described this herbivory quantitatively, measured the protein and phenol abundance, and identified potential herbivores in the laboratory. We sampled plants from 10 colonies of each species in the years 2007 and 2008. To quantify herbivory, we used an index of damage (ID), with six categories of injury from 0 (0%) to 5 (50-100%). Air-dried moss samples were weighed (100 mg) and used for protein and phenol detection by the Bradford and Folin-Ciocalteau methods, respectively. The plants were cultivated under controlled laboratory conditions and the identification of herbivores was performed from photographs. Injury was higher in H. tamarisci than in L. concinnum (68% and 38% in 2007 and 35% and 23% in 2008, respectively). H. tamarisci had higher mean ID (1.70 in 2007 and 1.09 in 2008); however, the ID values were low compared with ID values detected in angiosperms from tropical forests. Proteins were more abundant than phenol compounds for both species. H. tamarisci had the highest levels of protein and phenols. The phenol/protein ratios (ph/pt ratio) from H. tamarisci (0.42) and L. concinnum (0.40) were similar to those of other terrestrial plants. No correlation between ID and ph/pt ratio, proteins or phenols was detected. Lepidoptera larvae (Geometridae) and micro-snails (Charopidae) were found feeding mainly on the leaves of these mosses. Thus, H. tamarisci and L. concinnum are food sources for herbivores in the field, mainly as alternative food sources for some small and less mobile herbivores.332140147Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [03/12595-7, COTEC/IF 41.065/2005, IBAMA/CGEN 093/2005]