The MR-Linac opens the possibility for accurate daily treatment response monitoring. Quantitative MR imaging is a promising tool to quantify day-to-day changes. Therefore the performance of quantitative imaging of the MR-Linac needs to be assessed. In this study, we investigated the repeatability of T2 and ADC mapping using test-retest data of patients with prostate cancer. We calculated the within-patient coefficient of variation (wCV) and compare this to data from a conventional diagnostic 3T scanner. The MR-Linac performs similar to the diagnostic scanner regarding T2 mapping as wCV values are comparable. However, the repeatability for ADC mapping is lower on the MR-Linac.