Resumo. The aim of this study was to evaluate litter input and decomposition and root biomass of three forest fragments at different successional stages (advanced, medium and initial) in Pinheiral Municipality, in the state of RJ, Brazil. To evaluate litter input, 10 conic collectors were installed in each fragment. The root biomass was quantified by monolith method in two periods (wet and dry) at depths of 0-10, 10-20 and 20- 30 cm, and 10 samples were collected in each area. To evaluate the decomposition rate in each area, 12 litter bags were distributed. No significant differences were observed for litter input between the areas, but there was a tendency to increase litter input with successional evolution. No significant differences were observed for seasonal litter input between areas during the year, but there was a small increase in the months of July and August. At the advanced stage, litter input could be grouped into two periods: February to July, with lower values; and August to January, with higher values. The leaf fractions and reproductive material input were reduced, while branch and other fractions increased with succession. For litter decomposition, the intermediate stage showed the lowest decomposition constant (k) (0.0038 g g -1day-1) and the highest half life time (182 days) , followed by the initial (0044 g g -1day-1 and 154 days) and advanced (0.0064 g g -1day-1 and 108 days) stages. The root biomass in different areas and depths for both two periods studied showed higher values in the advanced stage, followed by the intermediate stage and the lowest values were found in the initial stage. The seasonal root biomass difference occurred mainly in the intermediate stage, with higher values in June.