Owing to the lack of precise and reliable mineralization ages, the origins of some sandstone-type U deposits (STUDs) are still debated. The unusual texture of U ore (commonly uraninite) and the difference between the chemical characteristics of U and its radiogenic daughter isotopes make U-Pb dating unsuitable for STUDs. However, STUDs are commonly rich in Re; therefore, Re-Os dating may be an alternative. Re-Os dating of two groups of pyrite samples from U ores in the Erlian sandstone-type U district yields two similar ages: 52.5 +/- 4.7 and 53.3 +/- 3.5 Ma. These ages are consistent with previous U-Pb ages (56.5 +/- 7.5 and 63 +/- 22 Ma) and demonstrate the reliability of sulfide Re-Os dating of STUDs. The pyrite Re-Os ages suggest that the Erlian STUDs formed at similar to 53 Ma, corresponding to the regional uplift of the Erlian basin during the Late Cretaceous-Early Eocene and the humid environment in the region during the Early Eocene Climatic Optimum.