The objective of this work was to evaluate the performance of cover crops as for biomass production and nutrient accumulation during the crop off-season in an oxisol in Cerrado, in Goiás State, Brazil. The experiment was performed in Rio Verde, GO, Brazil, from November, 2007 to October, 2008. It was used a randomized block design, with plots divided according to time, with cover crops, and subplots, concerning biomass sampling, with four repetitions. The evaluated cover crops were: Brachiaria ruziziensis, Pennisetum glaucum and B. ruziziensis + Cajanus cajan, and as a reference, fallow treatment with sponteneous species. The biomass samples were collected five times, since the desiccation date of P. glaucum, 60 days after cover crop sowing, which occurred on June, 12 th , 2008. The P. glaucum has shown the greatest amount of biomass and nutrient accumulation at 60 days after sowing, while the B. brizantha, B. ruziziensis and B. ruziziensis + C. cajan have shown significant accumulation in the end of the crop off-season.