Acute respiratory diseases (ARD) are the most common infections in humans and difficult to prevent. Viruses have been recognized as predominant ethiological agents. In Cuba, ARD constitute a major problem of health and are the first cause of morbidity and important cause of mortality. In this paper, rapid diagnosis was performed to 516 clinical samples which arrived to the Reference Respiratory Viruses Laboratory of the Pedro Kouri Institute of Tropical Medicine (IPK) from different parts of Havana City during 1995, 1996 and 1997. The results obtained have shown 218 positive samples (Influenza A, 89; respiratory syncytial virus 52; Influenza B, 45; Adenovirus, 13; human parainfluenza virus(HPIV)-1, 6; HPIV-2, 3 and HPIV-3, 10). Influenza A was the virus most frequently found in adults, whereas in closed population of teen-agers and adults, Influenza B was frequently found. Furthermore, respiratory syncytial virus was the most important pathogen in children\'s under 1 year of age.