Magnetic properties of polycrystalline Pr5Ge3 and Nd5Ge3 (hexagonal, Mn5Si3-type) compounds have been studied. Magnetization measurements in 0.5 T field indicate that the Pr5Ge3 orders antiferromagnetically at 18 K (TN). However, in an applied field of 10 mT, the zero-field-cooled and field-cooled magnetization bifurcates below ∼65 K. This and the positive paramagnetic Curie temperature, obtained from the Curie-Weiss fit to the paramagnetic susceptibility, suggest the presence of competing ferromagnetic and antiferromagnetic interactions. The magnetization versus field isotherm at 5 K shows an S-shaped curve and a weak tendency to saturation in fields of 9 T with negligible hysteresis. The magnetic moment attains a value of 1.6μ B/Pr3 at 5 K in 9 T. The magnetic entropy change near the magnetic transition has been calculated by measuring magnetization versus field isotherms close to TN. The entropy change is found to be considerably large. Neutron diffraction study indicates that below ∼43 K the Nd 5Ge3 has flat spiral ordering with wave vector K = [0, 0, ± 1/5] (the flat spiral axis coincides with cell parameter, a). Neutron diffraction study of Pr5Ge3 suggests that the magnetic structure of Pr5Ge3 could be similar to that in Nd 5Ge3. © 2011 American Institute of Physics.