Resumen: Se describe un brote de tuberculosis aviar en gallinas criadas a campo en la provincia del Chaco, al nordeste de Argentina. Las aves estaban emaciadas y en la necropsia efectuada a tres de ellas presentaron granulomas de diversos tamaños en diferentes órganos internos, contenidos bacilos ácido- alcohol resistentes. Histopatológicamente fueron diagnosticadas como tuberculosis. Se aislaron colonias de Mycobacterium avium subsp- avium en los cultivos, confirmado por técnicas de reacción en cadena de la polimerasa. Abstract: An outbreak of avian tuberculosis was detected in chickens from a rural area of Chaco Province, northeastern Argentina. The hens were emaciated and presented gramulomatous lesions of various sizes throughout the internal organs. The lesions observed in three necropsied birds consisted of granulomas containing alcohol/ acid- fast bacilli. All the lesions found were diagnosed histopathologically as tuberculosis, Mycobacterium avium sudsp. avium were isolated from the cultures and confimed by polymerase chain reaction technique.