We present maser polarimetric observations of the four ground-state transitions of OH, toward a sample of young planetary nebulae (PNe) using the Australia Telescope Compact Array. This sample includes five confirmed OH-maser-emitting PNe, three confirmed and one candidate H2O-maser-emitting PNe. Polarimetric observations provide crucial information related to the magnetic field in these sources. Maser-emitting PNe are very young PNe and magnetic fields are a key ingredient in the early evolution and shaping process of PNe. Our results suggest that magnetic field strengths may change very rapidly in young PNe.