Four nematode species (Physaloptera clausa Rudolphi, 1819; Ph. maxillaris Molin, 1860; Protospirura numidica criceticola Quentin, Karimi and Rodrigues De Almeida, 1968; Toxascaris leonina (Von Linstow, 1902) were collected from D. griseus, D. culpaeus and C. chinga in Neuquen Province, Argentina. These hosts were captured from April to August in 1990 and 1991. Ph. clausa and Ph. maxillaris ar redescribed. The systematic position of Ph. clausa is discussed and the authors conclude that this species could be considered the type species of the genus. The possibility that D. griseus and D. culpaeus could be the accidental hosts for P. n. criceticola is discussed. Prevalence, mean intensity and frequency of each species are given. These parameters were related with the diets of the hosts and the parasite life cycles. There was no relationship between parasitic burden of each host and their nutritional condition (Kendall Tau Test). Significant differences exist among the diet of each host and among prevalence values of each parasite species (Homogeneity Test SYSTAT Program).