To examine levels of heat shock proteins (HSPs) in host responses to helminth infection, rats were infected with Trichinella spiralis. The kinetics of HSP25, HSP60, HSP70 and HSP90 production in the liver and muscle of infected rats was compared with that of non-infected controls. HSPs were detected using electrophoretic analysis of fixed amounts of proteins (0.02 mg) and then blotting and incubation of membranes with polyclonal anti-HSP25 antibody, or monoclonal antibody against HSP60, or HSP70 or HSP90. Quantitation of blotted separated polypeptides reactive with the specific anti-HSP antibodies was achieved using an image analyser. Enhancement of HSP25 production was observed in the liver of infected rats, whereas muscle from the same rats exhibited enhanced production of HSP25 and HSP60 one day after infection only. These data indicate that HSPs levels can be used successfully to measure stress injury brought about by helminth infection in organs and tissues of the host.