We have synthesized a rare example of a uranium(IV) stannyl (kappa(4)-N(CH2CH2NSi(Pr-i)(3))(3)U(SnMe3), 1) via transmetalation with LiSnMe3. This complex has been characterized crystallographically and shown to have a U-Sn bond length of 3.3130(3) A, substantially longer than the only other crystallographically observed U-Sn bond (3.166 A). Computational studies suggest that the U-Sn bond in 1 is highly polarized, with significant charge transfer to the stannylate ligand. We briefly discuss plausible mechanistic scenarios for the formation of 1, which may be relevant to other transmetalation processes involving heavy main group atoms. Furthermore, we demonstrate the reducing ability of [SnMe3](-) in the absence of strongly donating ligands on U(IV).