• Lithium carbonate has been observed to induce neutrophilia in psychiatric patients and has been used in a number of childhood neutropenic disorders. We tried lithium carbonate in three children with glycogenosis Ib to see if the drug would alleviate the neutropenic complications of the disorder. Mean absolute neutrophil counts rose in one patient but not in the other two. Despite high-dosage schedules, serum lithium levels were highly erratic. Two patients developed potentially severe side effects, including polyuria, diarrhea, and altered mental status. One patient developed pneumonia despite a neutrophil count rise in response to therapy. Lithium carbonate is not useful in patients with glycogenosis Ib.