Crop association is defined as the growth and development of two or more species in the same place during a part or all of the vegetative cycle. Maize and bean association affect morphological and physiological attributes of both species, which is manifested in the biomass accumulated in the different compartments and, finally, in the yields. The aim of this research was to determine the accumulation and distribution of both maize and bean biomass in association with regard to their unicultivos. Varieties planted were: Bola commercial (FBR), Cargamanto rojo (FC), an elite line Bola roja (FBE) and the maize variety Montana regional, white cornel (M). Seven treatments were evaluated: four unicultivos for maize and bean (Mo, FBRo, FCO, FBEo) and three associations (MxFBR, MxFC, MxFBE). The experimental design was a completely randomized block. The dry weight variables: stems, leaves, pods and panicles, in maize associated with bean, decreased compared to unicultivo. The bean variety most affected negatively by the association, was the elite ball (FBE), in which the dry weight variables: stems, leaves and pods, were reduced compared with the unicultivo. The contribution of biomass to the plant beans, by the pods was greater in the association that in the unicultivo, except for the elite ball bean (FBE) variety.