In this article, we investigate the impact of BSE and bird flu on consumers' meat demand in Japan by using the 'almost ideal' demand system. The BSE and bird flu scares brought about a fall in demand for beef and chicken, respectively, and an upturn in demand for pork and fishery products, which are substitutes for beef and chicken in Japan. We also find that the bird flu outbreak had no impact on the market share for beef. This suggests that BSE had a larger impact on consumers' meat demand than did bird flu. Our empirical results also show that BSE has had a persistent impact whereas, bird flu has not. These differences might depend on the characteristics of each disease, such as the incubation period, cure rate and infection risk.