Preclinical mouse models that allow the evaluation of novel techniques in radiotherapy using charged particles like protons or heavier ions are discussed here. Focused beams of protons or carbon ions offer distinct physical characteristics that might contribute to an overall improved risk-benefit profile in radiotherapy. In the last decade, novel concepts in radiotherapy aimed to optimize the delivery of high radiation doses to the tumor while sparing the surrounding healthy tissue. 2D in vitro tumor cell cultures provide experimental models to determine the radiosensitivity of isolated cells to different radiation qualities. However, these cell culture models are not capable of mimicking the complexity and heterogeneity of 3-dimensionally growing clinical tumors with their individual tumor microenvironment. Therefore, small animal tumor models are urgently needed to study radiation responses after particle radiotherapy in vivo. Here we describe the recent developments and the accurate testing of novel techniques in particle radiotherapy using up-to-date preclinical animal models.