We study the impact of the 2015 mass arrival of refugees to Germany on residential housing rents. Using unique data on end of year county-level refugee populations and data on monthly offers of flats for rent from Germany's leading online property broker Immobilienscout24, we find strong evidence in difference-in-differences regressions for a negative effect of refugee immigration on rental prices. Adverse price effects, however, appear attenuated in the heyday of the crisis in late 2015 if a larger share of refugees is housed in decentralized accommodation. Various robustness checks corroborate our findings, including IV regressions that exploit for identification information on the pre-crisis location of refugee reception centers and group quarters.