The crystal structure of sparsentan has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional theory techniques. Sparsentan crystallizes in space group P-1 (#2) with a = 11.4214(8), b = 12.0045(9), c = 14.1245(12) Å, α = 97.6230(22), β = 112.4353(16), γ = 110.2502(11)°, V = 1599.20(6) Å3, and Z = 2 at 298 K. The crystal structure consists of an isotropic packing of dimers of sparsentan molecules, linked by N–H···O=S hydrogen bonds. Several intra- and intermolecular C–H···O and C–H···N hydrogen bonds also link the molecules. The powder pattern has been submitted to the International Centre for Diffraction Data for inclusion in the Powder Diffraction File™ (PDF®).