Abstract Aspiculuris tetraptera a pinworm of mice, is an important parasite in institutions with mice colonies for both research and teaching purposes. Infection with this parasite has impact on biomedical research. This is likely due to the availability of the parasite’s eggs in the environment, therefore can easily be transmitted and infection is generally asymptomatic. No information regarding the prevalence, morphology or phylogeny is available on A. tetraptera from Saudi Arabia. A group of 50 laboratory mice were investigated for the presence of A. tetraptera. Worms were described morphologically and molecular characterization was attempted using 18S rRNA and Cytochrome Oxidase Subunit I genes. The prevalence of A. tetraptera infestation in the laboratory mice examined was found to be 46%. Morphological description indicated that the worms belong to A. tetraptera and this was confirmed by molecular characterization. Both regions studied have shown that the worm under investigation grouped with A. tetraptera. 18S rDNA sequences obtained in the present study showed high identity with sequences from A. tetraptera while Cytochrome c Oxidase subunit I gene (COI) sequences showed intraspecific variation resulted into two haplotypes from the isolates in the present study. A. tetraptera was recorded for the first time from Saudi Arabia. Molecular characterization has shown, based on the COI sequences, that the Saudi isolates of A. tetraptera are distinct.