In the title compound, C(12)H(13)N(3)O(2)S, the oxazolidin ring displays an envelope conformation. The dihedral angle between the benzimidazole ring and the 1,3-oxazolidin-2-one mean plane is 69.85 (13)°. In the crystal, mol-ecules are linked by inter-molecular N-H⋯N hydrogen bonds, forming a chain parallel to the b axis.