This article discusses agribusiness market risk management, the influence of agribusiness cooperatives on this practice and assesses the portfolio of agricultural production commodities in the Brazilian state of Paraná regarding the risk-return relation. Through outlining an efficiency frontier, it was possible to determine the necessary changes to be carried out in the state production portfolio aiming at economical efficiency (defined, in the context of this work, as the trade-off between risk and return). The article also assesses the participation of agribusiness cooperatives in the production of items included in the model and the possible influences this type of organization could exert on changes addressed to economical efficiency. Through questionnaires and interviews with cooperative managers, it was possible to assess the cooperative willingness to motivate changes on their production and their member portfolios. It was also possible to verify that the main reasons influencing decisions on production preference changes are related to economical and rational aspects, such as cooperative strategic focus and member resistance. Reasons related to political or social aspects are inherent to the cooperative organizational characteristics, however, in the Paraná’s context these reasons do not exert significant influence on diversification decisions considered as market risk management tools.