Paractinolaimus sahandi n. sp., found in wet soil samples collected from the rhizosphere of grasses of Sahand Mountains, Iran, is described. This new species is characterized by its long body (3.5-4.7 mm), high a value (74.5-88.5), anterior location of posterior subventral nuclei, occupying 62.5-68.0% of glandularium distance, the presence of 1-4 pre- and 1-3 post-vulval papillae and numerous tiny, not innervated papillae in front and behind the vulva in the outer layer of cuticle; common functional males in the population, with 62.5-81.3 μm long spicules and 15-17 ventromedian supplements. The new species, which is the only one in the genus showing the advulval cuticular tiny papillae and is unusually slender, is compared to four species of Paractinolaimus, namely P. macrolaimus, P. longidrilus, P. spanithelus and P. rafiqi. The ribosomal 18S rDNA (1246 bp sequenced) and 28S rDNA D2/D3 region (844 bp sequenced) of P. sahandi n. sp. were sequenced for molecular characterization. Sequences of the 18S and 28S D2/D3 of P. sahandi n. sp. have distinct differences from those of the only sequenced P. macrolaimus, with 6 bp differences in 18S and 38 bp differences and five gaps in 28S. This is the first report of the occurrence of members of Actinolaimidae in Iran.