The crystal structure of the system PrjMi-4BaCuOsFe has been recently reviewed. Tfie magnetic structure of samples with x = 0 aiidx = 1 is mainly due to effective local moments of iron and copper. In Pr-rich samples, Fe ions occupy two non-equivalent positions, making it substantially plausible that two or more magnetic subsets might coexist in the system. This contribution presents magnetization studies on five samples of the PrjMi. xBaCuOsFe system (x = 0. 0, 0. 2, 0. 5, 0. 7 and 1. 0). All samples exhibit a strong irreversible behavior between zero-fieldcooled and field-cooled procedures below a certain irreversibility temperature 7-4 Above Tk both branches are coincident and well described by a Curie-Weiss fitting. Decreasing the temperature below TJ, the zero-βeld-cooled response increases less than the field-cooled curve, indicating some degree of frustrated antiferromagnelic couplings.