A male infant with transient severe neutropenia and defective neutrophilic mobility is described. He had recurrent upper respiratory infections that responded well to antibiotics. The neutrophilic counts continued to be less than 300/cu mm, and neutrophilic random mobility and chemotaxis were persistently defective during early infancy but were normal at 16 months of age. No ultrastructural abnormality was found in the neutrophils. Phagocytic and bactericidal abilities of the cells were not impaired. Bone marrow was normal. The clinical and laboratory findings suggest that this disorder is transient "lazy-leukocyte" syndrome.