A previously reported recombinant lambda Ts39 fusion protein (FP) derived from Trichinella spiralis larvae was purified by affinity chromatography using an anti-beta-galactosidase antibody conjugated column and the effect of FP on induction of a protective response in mice was studied. BALB/c mice were injected three times at weekly intervals with FP emulsified in an equal volume of Freund's complete adjuvant and one week after the last injection mice were each challenged with a lethal dose of 1200 L1 larvae of Trichinella spiralis. As a result, the FP induced significant protection. Mice were also infected orally with 250 L1 larvae each after injection of the FP. On the 35th day of infection, immunized mice with the FP harboured 78% fewer muscle larvae than saline controls. Also, the numbers of adult worms in the small intestine were smaller in FP injected mice than saline controls on day 6 and 9 of the infection. These results suggest that the recombinant lambda Ts39 FP is a potentially valuable antigen for vaccine development.