Proleptonchus aestivus and Tyleptus projectus from Cuc Phuong natural forest are described and illustrated for the first time in Vietnam. Proleptonchus aestivus species is characterized by its body mm long; lip region cap-like with lips amalgamated and papillae little protruding; odontostyle very slender and odontophore rod-like, arcuate; female genital system mono-prodelphic; tail short and rounded, hemispheroid. Tyleptus projectus species is characterized by its body mm long; lip region set off by marked depression or weak constriction; six lips conspicuous projecting liplets around the oral opening; odontostyle small but robust, odontophore rod-like; female genital system monoopisthodelphic, male genital system diorchic, with opposite testes. Tail short and rounded, to hemispheroid. | Two new recorded species of the family Leptonchidae (Nematoda: Dorylaimida) for Vietnam’s fauna from Cuc Phuong national park