Hassalstrongylus is a genus of nematode worms that infect mostly muroid rodents from eastern North America to South America. The genus is part of the Nippostrongylinae and related to genera like Stilestrongylus. The proposed species Hassalstrongylus multiovatus, described from Akodon simulator, is a synonym of Trichofreitasia lenti from Oligoryzomys flavescens.