Background: Influenza causes high mortality in the elderly. Its behavior has not been studied regularly in tropical and subtropical countries, like Cuba. The purposes of this study were to understand the circulation type and subtype of the influenza virus and to obtain evidence of their relationship with underlying P&I deaths in persons aged 65 years or older. Methods: A retrospective study was carried out with 7,252 positive sera from influenza A(H3N2), A(H1N1) or from type B by hemagglutination inhibition assay from 1983-1984 and 2004-2005 seasons, which created three series with the type/subtype prevalence percentages corresponding to the total of positive cases. The relationship between mortality by pneumonia and influenza in people aged 65 years or more was determined by calculating its mean rates when the type/subtype prevalence was above the median or not. Results: The circulation pattern of these viruses in Cuba was defined, and predominance of A(H3N2) in the 77% of seasons was corroborated. The mean rate of mortality increased 24.4% (p < 0.001) when any pair of virus was above its medians and for the subtype A(H3N2) the increase was of 14.6% (p < 0.05). Conclusions: For the first time the Health Authorities of Cuba received a "native" pattern on the circulation of influenza viruses in the period studied, showing increases in mortality for underlying pneumonia and influenza in people aged 65 years or older when the A(H3N2) or any pair of viruses were above their means and underscoring the need for better prevention measures and vaccination programs for elderly people in our country.