Four Gumboro disease (IBD) outbreaks were identified between February and June 1993 in the Antananarivo area (Madagascar) exhibiting the largest commercial poultry production activity. Affected birds were 3 to 5 weeks old, the mortality rate ranged from 5.70 to 27.4%. Typical symptoms and gross lesions were observed, necrotic degeneration of bursal follicles was also detected. By means of agar-immunodiffusion test, IBD viral antigen was demonstrated. Since the IBD has never been recorded in the country before, the probability of an external origin through the importation of day-old chicks is high.