ABSTRACT. Two-day-old specific-pathogen free chicks were inoculated with type A influenza virus (A/whistling swan/Shimane/499/83 (H5N3)) through the air sac. Inoculated chicks showed mild to severe diarrhea and lesions of pancreatitis and atrophy of the pancreas, thymus and bursa of Fabricius. One chick died on each of days 4, 6 and 14 postinoculation (PI). Reduced weight gain was conspicuous from day 22 PI. Positive immunoreaction to the virus antigen was detected in the pancreas, kidneys, liver, lungs and air sacs, and cecal lamina propria. Virus recovery persisted longer in the pancreas. Some of these findings conformed to those of stunting syndrome. -KEY WORDS: avian influenza virus, chick, stunting syndrome.