Parabronema skrjabini is a spirurid nematode of the family Habronematidae that lives in the abomasum of ruminants such as sheep and goats. The purpose of this study was to investigate the molecular aspects of Parabronema skrjabini in sheep. The worms were collected from sheep in Sanandaj (west of Iran). The first internal transcribed spacer (ITS) of ribosomal DNA (rDNA) nucleotide fragments of Parabronema skrjabini were amplified by polymerase chain reaction (PCR) using two pairs of specific primers (Para-Ir-R and Para-Ir-F). ITS1 homology in the sequence of this study was 69% compared with the sequence data in GenBank. To our knowledge, this is the first study in the world exploring the genetic diversity of P. skrjabini in sheep based on ITS1.