A slaughtered broiler chicken, 46 days of age, af fected with an esophageal duplication cyst was subjected to pathological investigation. An ellipsoidal cyst, measuring 4 cm in its greatest dimension, was closely attached to the esophageal region connected with the proventriculus, compressing the region. The cyst was unilocular and its cavity was filled with mucus containing purulent exudate. Histologically, the cystic wall consisted of lining epithelia, subepithelial connective tissue including mucous glands, two layers of smooth muscular tissue and fibrous capsule. Lining epithelia were stratified squamous. The results suggest that the cyst is lined with mucosa similar to the esophageal or crop mucosa. The cyst was complicated with pur ulent inflammation with ulcer. The present case suggests that esophageal duplication cysts should be considered in the dif ferential diagnosis of cystic lesions closely attached to the esophagus in chickens.