Two new species of Syphacia (Nematoda: Oxyuridae) are described from endemic murids of Sulawesi, Indonesia: Syphacia (Syphacia) taeromyos sp. n. and S. (S.) paruromyos sp. n. parasitic in the caecum of Taeromys celebensis and Paruromys dominator, respectively. They are readily distinguished from all of the congeners recorded from Indonesia-Australian regions by having a round cephalic plate, vesicular lateral alae in the male, posteriorly positioned excretory pore in the male, and/or lacking cervical alae. Syphacia (S.) paruromyos differs from S. (S.) taeromyos by having a whip-like tail appendage in the male, longer relative distance between excretory pore and vulva, and larger eggs. The round cephalic plate in both sexes and developed vesicular lateral alae in the male are morphological traits common in endemic Syphacia species hitherto known from Sulawesi murids, suggesting that they have derived from a common ancestor and evolved with their hosts in the isolated insular environment.