We present 4 patients with pulmonary alveolar proteinosis and AIDS which died in Infectious Disease Hospital Iaşi in the interval January 2002-March 2003. The pulmonary tissue from the necropsy exam was stained with H.E., PAS, Alcian blue and Mucicarmine. The macroscopical examination revealed multiple yellow-gray nodular areas (>2 cm) of consolidation. Microscopically, the alveoli were filled with a delicate, granular, acidophil material that was periodic acid Schiff (PAS) positive. The intraalveolar material was Alcian blue and Mucicarmine negative, too.