Studies of dilute Fe-57 as a diamagnetic probe in RMn(2)Si(2-x)Ge(x) (R = La, Sm, Gd) show that the ferromagnetic compounds, with R = La, Sm and T-c similar to 320 K, are antiferromagnets above T-c, with T-N similar to 450 K, similar to T-N in the heavy rare earth compounds. At the phase transitions, changes in the easy magnetization axes are observed.