Objective: To examine changes in pneumonia occurring in infants over the past 150 years Methods: A literature review based on Pál Heim's observations published in 1914 and 1926, supplemented with current international publications. Results: In the early 20rh century, the winter peak in infant mortality was largely driven by respiratory infections, particularly pneumonia, with mortality rates reaching 10-40%. Today, in developed countries, the in-hospital case fatality rate is below 1%. lmprovements in living conditions, together with advances in diagnostics and therapeutic options, have significantly improved patient outcornes. Pál Heim's timeless observations regarding the influence of seasonality, malnutrition, bronchiolitis danger signs, positioning and nursing care, as well as the importance of education and prevention, remain highly relevant. Conclusion: A careful, patient-centered clinical approach, supported by attentive nursing and prevention strategies - Heim's enduring legacy - continues to play a decisive role in the management of infant pneumonia.  Kulcsszavak: infantile pneumonia, Pál Heim, epidemiology.