Two types of phagocytic cells participate in host defense against bacteria: PMNs and MNPs. Their normal functions include mechanisms for specific attachment, ingestion and killing of bacteria, and direct cellular mobility to bring them into an area of bacterial invasion. Acquired or genetic defects in any of these processes result in inadequate control of bacterial growth. Among disorders associated with acquired defects of phagocytes are: kwashiorkor, bacterial endocarditis, myelogenous leukemia, diabetes mellitus, systemic mycoses, advanced malignancy, and acute alcohol intoxication. Among disorders associated with genetic defects of phagocytes are: chronic granulomatous disease, familial lipochrome histiocytosis, Job syndrome, Chediak Higashi syndrome, lazy leukocyte syndrome and myeloperoxidase deficiency. The cellular phagocytic defects in these disorders are reviewed.