Severe pneumococcal pneumonia may precipitate both respiratory failure and neutropenia. The prognoses are considered to be very poor in such cases. We encountered three patients with pneumococcal pneumonia presenting respiratory failure and neutropenia, and successfully treated two. All three patients showed disseminated intravascular coagulation, and respiratory failure requiring mechanical ventilation. Neutropenia was treated with granulyte-colony stimulating factor (G-CSF), with methylpredonisolone administered by pulse therapy for 3 days to treat severe respiratory failure during the clinical course. All 3 patients were relieved of their respiratory failure at least for a few days following treatment. As a result of treatment with antibiotics and G-CSF, pneumococci disappeared from the patients' sputum. However, it has been reported that disintegration of the bacterial cell walls can release inflammatory components capable of causing secondary inflammatory reactions in the lung tissue. This suggested that the worsening respiratory failure experienced by our patients during their clinical course was a result of such reactions, and that methylpredonisolone was effective as the treatment of inflammation.