Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) are advanced magnetic resonance imaging (MRI) techniques that are based on differences in the diffusion rate of water molecules in brain tissue. DWI and DTI are widely used in pediatric neuroradiology to evaluate a wide spectrum of brain diseases. The interpretation of DWI and DTI images requires a basic knowledge of the underlying physics to detect potential pitfalls and avoid misinterpretation. Several DWI pitfalls are related to the dependency of DWI images not only on the diffusivity of water molecules, but also on various additional MRI phenomena such as the T1- and T2- relaxation characteristics and MRI-related artifacts. In addition, knowledge about the age of the child and interval between the onset of injury and acquisition of DWI/DTI images is important. Finally, qualitative evaluation (“eye-balling”) maybe misleading, and the application of quantitative measurements of DTI scalars may avoid misdiagnosis.