Children with recurrent lower respiratory tract infections are often a challenge for their physicians. This article reviews the differential diagnosis of recurrent cough, bronchopneumonia and/or pneumonia in children and emphasizes on the necessity of preventing long-term complications of these infections. It also suggests a step-wise immunological work-up, which includes investigating a possible immune maturation delay or deficiency which could explain these symptoms. This work-up focuses on measuring antibody responses to pneumococci, followed by immunization when necessary, to rule out B cell dysfunction. Finally, this article also describes an upcoming study in Switzerland which will evaluate in 2005 the clinical and immunological outcome of these young patients.