This study conducted sentinel surveillance of influenza-like illness (ILI) in two cities in Ecuador, Guayaquil and Quito, from 2006 to 2010. The objective was to identify viral agents associated with ILI, describe circulating influenza strains and their epidemiological characteristics, and perform molecular characterization of those strains. A total of 1,702 ILI cases were studied, with nine viral agents detected in 597 patients. Seven genetic variants of influenza circulated in Ecuador, causing six periods of increased activity. Guayaquil showed more heterogeneity in the causes of ILI compared to Quito. Influenza was a common cause of ILI, causing more than one outbreak per year. There was no well-defined influenza season, with periods of no influenza activity alternating with epidemics of different variant strains. The study found that influenza A was the most common cause of ILI, with H3N2 and H1N1 strains circulating. Influenza B was also detected. The study also identified other viruses such as parainfluenza, adenovirus, and RSV. Antiviral resistance patterns were analyzed, with some strains showing resistance to oseltamivir and amantadine. The study highlights the importance of influenza surveillance in tropical regions, where influenza activity is less predictable and seasonal. The findings suggest that Ecuador may play a role in the global influenza epidemic, with genetic diversity and potential for viral reassortment. The study also emphasizes the need for improved surveillance and public education on the proper use of antibiotics. Limitations include potential age bias in the study population and the use of less sensitive sampling methods for viral detection. The study provides valuable insights into the epidemiology and molecular characteristics of influenza in Ecuador, contributing to the understanding of influenza in tropical regions.This study conducted sentinel surveillance of influenza-like illness (ILI) in two cities in Ecuador, Guayaquil and Quito, from 2006 to 2010. The objective was to identify viral agents associated with ILI, describe circulating influenza strains and their epidemiological characteristics, and perform molecular characterization of those strains. A total of 1,702 ILI cases were studied, with nine viral agents detected in 597 patients. Seven genetic variants of influenza circulated in Ecuador, causing six periods of increased activity. Guayaquil showed more heterogeneity in the causes of ILI compared to Quito. Influenza was a common cause of ILI, causing more than one outbreak per year. There was no well-defined influenza season, with periods of no influenza activity alternating with epidemics of different variant strains. The study found that influenza A was the most common cause of ILI, with H3N2 and H1N1 strains circulating. Influenza B was also detected. The study also identified other viruses such as parainfluenza, adenovirus, and RSV. Antiviral resistance patterns were analyzed, with some strains showing resistance to oseltamivir and amantadine. The study highlights the importance of influenza surveillance in tropical regions, where influenza activity is less predictable and seasonal. The findings suggest that Ecuador may play a role in the global influenza epidemic, with genetic diversity and potential for viral reassortment. The study also emphasizes the need for improved surveillance and public education on the proper use of antibiotics. Limitations include potential age bias in the study population and the use of less sensitive sampling methods for viral detection. The study provides valuable insights into the epidemiology and molecular characteristics of influenza in Ecuador, contributing to the understanding of influenza in tropical regions.