We describe a case of linear IgA bullous dermatosis (LABD) in a patient with acute lymphocytic leukemia during treatment with granulocyte colony-stimulating factor (G-CSF). After a drug eruption due to imipenem cilastatin sodium had disappeared, bullous lesions appeared on the trunk. Results of histopathological studies and direct immunofluorescence studies of the lesion were consistent with LABD. Reinstitution of G-CSF after the resolution, however, did not reproduce the bullous eruptions. This suggests that in addition to G-CSF, the presence of precipitating factors that can synergistically enhance or accelerate the outbreak of the disease is required for the development of bullous lesions. Various cytokines, such as interleukin-2 (IL-2) and interferon-gamma (IFN-gamma), endogenously produced from activated lymphocytes during the drug eruption might have provided a favorable milieu for the onset of G-CSF-induced LABD. We suggest that patients with LABD will need special attention with respect to the type of cytokines or combination of cytokines given as therapeutic modalities.