The presence of Cryptosporidium spp. was detected in broiler chickens of 32-40 days of age, colonizing the bursa of Fabricius. The histologic study with haematoxylin and eosin staining was done on specimens of trachea, complete intestinal tract and bursa. Samples of intestinal content were also studied using Kinyoun staining technique. All birds with signs of illness were positive to the presence of parasite, showing a hypertrophic bursa of Fabricius, filled with caseous content. The bursal epithelial cells were full of different developmental stages of Cryptosporidium spp. This note describing the presence of Cryptosporidium spp. in industrial flocks of broiler chickens, is the first report of this parasite in Uruguay
