Recent studies have suggested that specific granules and/or their contents may have a role in neutrophil adherence, oxidative metabolism, and other aspects of cell function. In the current report, we studied neutrophil function in a 13-year-old female with recurrent pyogenic infections and absent specific granules previously documented by electron microscopy. Levels of cobalamin (vitamin B₁₂)-binding protein and lactoferrin were markedly decreased in this patient's neutrophils. Bactericidal activity againstEscherichia coli was decreased at 60 and 120 min (percentage organisms killed: patient neutrophils, 48 and 33%; control neutrophils, 90 and 99%, respectively). Defective killing ofStaphylococcus aureus was also documented. Degranulation and adherence were normal. Levels of lactoferrin and cobalamin-binding protein were decreased in plasma but normal in saliva, indicating that the defect was specific for hematopoietic tissue. Superoxide anion production was normal in the patient, while hydroxyl radical generation was decreased in response to opsonized zymosan. The data support the concept that specific granules and their contents are important for oxidative metabolism and other neutrophil functions.