The effect of lithium treatment on the impaired neutrophil chemotactic function of a patient affected by Shwachman-Diamond syndrome is reported. We found that (1) a cytoskeletal cellular defect seems to be involved in the impairment of neutrophil function (and perhaps of cellular secretion and chondrocyte function) in the syndrome; (2) intermittent neutropenia is always present in the syndrome, and (3) lithium seems capable, in addition to its capacity of inducing leukocytosis, of modulating leukocyte functions by modulating the microtubular system. The drug, at usual therapeutic dosage, was able to normalize neutrophil functions without side effects. As no therapy is available in this syndrome to date, our data suggest the therapeutic use of lithium in order to improve these cytoskeleton-mediated functions and the degree of neutropenia.