Immunisation of rabbits against tsetse flies was attempted by injecting homogenized intestines or crops of these flies (Glossina fuscipes fuscipes) together with Freund's complete or incomplete adjuvant. The effect of the inoculations was assessed by monitoring the mortality and reproductive performance of flies fed on these rabbits. The results show only a modest but statistically significant increase in mortality in the batches of flies fed on immunized rabbits as compared to controls.