Infectious diseases are common in the elderly and are a source of significant morbidity and mortality, as well as an additional cost for public health. The aim of our work was to determine the epidemiological, clinical and paraclinical particularities of infectious pathologies in the elderly. Through a retrospective study including 30 patients aged 65 and over hospitalized in an internal medicine department in Tunis for infections, we report a semiological and etiological polymorphism. Several risk factors favoring infection were identified: polypathology, polymedication, undernutrition, diabetes, anemia, advanced age greater than or equal to 80 years and immunosuppressive treatment.