It was proved that infetifous bursal disease certainly existed in chicken flcdrs of Taiwan and caused severe economic lcGs, The clinical signs and pathologic changes observed from several outixeaks in Taiwan were similar to thccse of descrikal by workers of other countries. The causal agent were isolatl from naturally affected chickens and identifIed as infectious bursal disease (ED) vms with agar gel precipitation test. Serologic study showed that antibcdy against ED virus resisted in survivors for 1 year or longer. General serologic survey of chicken I lois in Taiwan indicatlthat 1(0% of thebxrflcdrs and94.1% ofthebxoilerflocks were contamina1 with lED viurs. Totally calculated, 57.74% of the chickens were pasitive in ED antibcdy.