These studies were carried out the observation of polymorphonuclear leukocyte phagocytosis of Candida albicans in vitro and also detected to the cytoplasmic changes of polymorphonuclear leukocyte during phagocytosis by the method of electron microscopy. The results were summarized as follows: 1. In normal polymorphonuclear leukocyte, nuclear lobes showed a preponderance of dense, granular chromatin located peripherally. The cytoplasm of polymorphonuclear leukocyte was not extensive; the cytoplasmic matrix was moderate dense and of a granular appearance. Golgi complex and rough endoplasmic reticulum system was poorly developed. But a various type of granules were seen abundantly. 2. After 30 minutes of incubation, Candida albicans was completely engulfed. These had come to lie in the vacuole which was limited by the membrane. 3. After 90 minutes of incubation, the phagocytic vacuoles were larger, and many granules devoid of membranes were seen within them. Though the granules has lost their membrane after entering the vacuoles. 4. After 2 hours of incubation, the cytoplamsic components of polymorphonuclear leuko cytes were changed their original morphology.