The function of alveolar macrophages (AMS) in patients with pneumonia (n = 7) (Group A) and chronic obstructive pulmonary disease (COPD) (n = 11) (Group B) was investigated by evaluating the rate of phagocytosis and of the intracellular killing. A control group of healthy subjects (n = 8) was also included. Phagocytosis frequency (PHF), phagocytosis index (PHI) and intracellular killing towards Candida albicans were then evaluated. PHF and PHI were found to be significantly (p < 0.05) lower in Group B patients than in the control group, while intracellular killing showed a behaviour similar to controls. PHF and PHI values observed in the patients of Group A and in the control group did not show any significant difference; the intracellular killing rate proved on the contrary to be significantly (p < 0.05) lower than that observed in the controls.