A total of 108 toads and frogs were collected by hand from January to August 1994 from different sites in the southwest of Iran, mainly from Khouzestan province. Among 79 green toads (Bufo viridis), 93.7% were infected with one or more parasite species. There was no significant difference between snout-ventral lengths (SVL) of infected (n = 74) and uninfected (n = 5) toads (P = 0.323; Student’s t-test), also between the rate of infection in males and females (P = 0.392; χ2 test). Helminth parasites of B. viridis were the monogenean, Polystoma viridis; the digenean, Haplometra cylindracea; the cyclophyllid cestodes, Nematotaenia dispar; Diplopylidium acanthotetra cysticercoid and the nematodes, Cosmocerca ornata, Cosmocerca commutata, Rhabdias bufonis and Aplectana sp. There was no significant difference between the rate of infection with P. viridis (χ2 = 1.92, P = 0.166) and N. dispar (χ2 = 0.032, P = 0.859) in males and females. Males (n = 12), however, were significantly more infected (χ2 = 5.52, P = 0.019) with R. bufonis than females (n = 8). SVL of B. viridis infected with N. dispar and uninfected samples were significantly different (P = 0.016). No significant difference was showed for infection with P. viridis (P>0.05; Student’s t-test). Among 17 marsh frogs (Rana ridibunda ridibunda), 58.8% were infected with helminth parasites. There was no significant difference between SVL of infected (n = 10) and uninfected (n = 7) frogs (P = 0.238; Student’s t-test) and also between uninfected males and females using (P = 0.201; χ2 test). Metacercarian cysts of digenetic trematode Codonocephalus urniger and the nematode Aplectana sp. were found in Rana ridibunda ridibunda specimens. Twelve true tree frogs, Hyla arborea savignyi were examined. The monogenean, Polystoma viridis; the cyclophyllid cestode, Nematotaenia dispar and the nematode, Aplectana sp. were found in the tree frogs.