Helminth fauna of conventionally maintained hamsters from institutional ani
mal houses that supply the research community with laboratory animals and f
rom an openly kept control group, randomly purchased in a pet shop in the S
tate of Rio de Janeiro, were evaluated and compared. Necropsied animals fro
m institutional suppliers were infected with the oxyurid nematodes Syphacia
criceti and S. mesocriceti and with the cestode Rodentolepis, nana; those
from the pet shop were infected with S. mesocriceti and R. nana. These are
the first morphometric data that are based on Brazilian samples of these sp
ecies parasitizing hamsters. Mesocricetus auratus is a newly recorded host
for S. criceti, previously recovered from Oryzomys subflavus and Calomys ca
llosus in Brazil. The potential of pet and laboratory hamsters in the sprea
ding of helminth infections to humans is also considered.