RESUMEN
In November, 1996, there was an outbreak of acute respiratory infection in children under 3 in the province of Santiago de Cuba. 7 samples of nasopharyngeal exudates were received to determine the causal agent of the outbreak by indirect immunofluorescence technique (4 positive samples, 57.14). They were inoculated in MDCK cells culture and those cases that presented positive hemadsorption (6 isolates, 85.71) were analyzed by indirect immunofluorescence techniques (6 positive samples, 100) and immunoperoxidase (5 positive samples, 83.3). All the positive samples were classified as influenza A (subtype H3N2) which confirms what is reported in literature in relation to the circulation of this virus during that year at the national and international level. This paper allowed to know the causal agent of the studied outbreak of acute respiratory infection and to determine the circulation of the influenza A subtype H3N2 in that province.