The authors have investigated the polarization reversal on ferroelectric thin films caused by a grounded tip on 50-nm-thick Pb(Zr,Ti)O3 films. Backswitching occurred when the grounded tip recontacted a “freshly” switched area. It is believed that the upper part of the film switches back due to the field between the grounded tip and previously injected charges. During dynamic operation, partial backswitching was observed during pulsed writing using pulse widths of 1 ms. The results show that polarization reversal is an issue, which has to be addressed in the writing scheme of future probe-based storage devices.