We have measured the stray fields of thin permalloy (Ni 83 Fe 17 ) microstructures with different geometries and several thicknesses by magnetic-force microscopy ͑MFM͒. The MFM images are compared to corresponding images calculated from micromagnetic simulations. In particular, the type of 180°domain walls is discussed. We observe a transition from cross-tie to asymmetric Bloch walls between 70 and 100 nm film thickness. Good agreement between measurement and simulation is obtained.