In order to identify some nematodes in northern forests of Iran, several soil and tree bark samples were collected from northern forests of Iran, during periodic sampling from 2015 to 2017. After recording the information of samples, the samples were transferred to laboratory of Nematology at Tarbiat modares universuty. Nematodes were extracted using tray method, killed and fixed following De Grisse’s (1969) method. Temporary and permanent microscopic slides of nematodes were prepared and studied using morphological and morphometric characters. Molecular studies using partial 18S rDNA and 28S rDNA D2/D3 sequences by both the Bayesian and maximum likelihood analyses were done. Two species of genera Hexatylus and Paurodonus were identified. H. viviparous, recovered from forests of Sehezar in Mazandaran province, characterized by short body, four lines on lateral field, short stylet with distinct knobs, median pharyngeal bulb without central valve, basal pharyngeal bulb with dorsal overlapping on intestine, position of vulva at 84.4-85.2, absence of post-vulval uterine sac (PUS) and long conical tail, 55-67 µm with pointed tip. In this study, male population of this species was not found. In comparison between Iranian population with other reported populations of the world no significant difference was observed. Paurodontus similis, the second species reported in this study, was recovered from forests of Gilan province. This species having short body, four lines in the lateral field, short 8.1-9.6 µm long stylet with small posteriorly directed knobs, weak metacorpus without a valve, pharyngeal basal bulb having an extension, ventrally extended into the intestine, short ca. 1.0-1.5 corresponding body width long PUS and elongate conoid tail with pointed terminus. Male population of this species was not found. In comparison between Iranian population with original description by Siddiqi, 1961 no significant difference was observed. Phylogenetic analyses using 18S rDNA showed that H. viviparous and P. similis have a close relation with Hexatylus sp. and Ficotylus congestae, respectively. Phylogenetic studies using 28S rDNA D2/D3 sequences showed that H. viviparous formed a clade with Nothotylenchus sp. and Paurodontella auriculata, also Paurodontus similis formed a common clade with F. congestae based on current molecular data.