The objective of this research study was to determine the relationship between knowledge about acute respiratory infections and preventive practices in mothers of children under five years of age treated in a health facility Iquitos, 2023; It was a descriptive, correlational study, non-experimental design study that worked with a sample of mothers of 91 children under five years of age, the technique for collecting data was the survey and the instrument was a questionnaire. The results were: the knowledge of the mothers of children under five years old was; 94.5% high, 5.5% medium and low 0.0%; Preventive practices were adequate in 87.9% and inadequate in 12.1%. When relating the variables, it was found that there is a significant statistical relationship between knowledge and preventive practices (p=0,001); Concluding: that there is a relationship between knowledge and preventive practi...