Acute respiratory infections (ARIs) are among the leading causes of childhood morbidity and mortality in Africa. The effects of climatic factors on occurrence of ARIs in the tropics are not clear. During the years 2006-07, we reviewed the clinical registers of the Chantal Biya Foundation (CBF), Yaoundé, Cameroon, paediatric hospital to investigate the association between climatic factors and ARIs in children. Our findings show that rain, high relative humidity and low temperatures are directly associated with an increase in the frequency of hospitalization from ARIs. Given the high frequency of hospitalization from ARIs we suggest that influenza vaccination campaigns should be implemented taking into account the seasonality in Cameroon.