A new species of Impatiens L., I. oblongipetala K. M. Liu & Y. Y. Cong (Balsaminaceae), from Yunnan Province, China, is described and illustrated, including its seed and pollen micromorphologies. This species is similar to I. lecomtei Hook. f. and I. weihsiensis Y. L. Chen, but differs by the white to slightly pink lateral sepals, the white lower sepal without purple striae, and the lateral united petals with apically retuse distal lobes.