The patients were a 59-year-old man and 68-year-old man with previously-treated small cell lung cancer (extensive disease). Amrubicin (40 mg/m(2) and 45 mg/m(2)) was administered for 3 days after brain irradiation. Severe neutropenia continued for nine days from day 8 following administration. Although both patients had an infection, it improved by granulocyte-colony stimulating factor (G-CSF), and antibiotics, plus a blood transfusion. Particular attention for severe myelosuppression should be given to amrubicin therapy with previously-treated small cell lung cancer. However, a detailed blood test in course 1 and early administration of drugs such as G-CSF make this therapy feasible. In addition, to control the condition of patients, repeated administration of amrubicin with dose reduction is recommended.