An experimental study was undertaken to determine cell afflux in the lungs of mice Intranasally Infected with viable P. brasiliensis candia. The cellularity of broncoalveolar lavage fluids was Investigated from the first to the 28th week post; challenge; in comparison with non-infected control animals, the cellularity of the challenged mice was very high all throughout the experimental period. Macrophages predominated during the first week post-infection, diminished abruptly after 4 week but regained and maintained their position after-wards. PMN's experienced a sudden and marked Increase at week 4 post challenge but were present in low numbers thereafter. giants cells were late comers; Lymphocytes varied little during the observation period. P. brasilenensis was recovered from every one of the Lavage fluids; 75% of the yeast cells were phagocytized by macrophages and the remaining, by giant cells. The results Indicate that macrophages and Lymphocytes Interact In an effort to control the fungus but fail to do so. This results in the establishment of a chronic disease.