The schizogony of Polychromophilus was partially known by the findings of Schingarew, Mer and Goldblum who demonstrated microschizonts in the reticulo-endothelial tissue. The present work completes these data by showing the presence of macroschizonts in the lungs of both African and European species. These schizonts are characterized by their large size, the hypertrophy of the host cell and its nucleus and the evolution of the parasite apparently slow when young, becoming rapid later.