Twenty-two non-neutropenic adult patients with Streptococcus pneumoniae meningitis received granulocyte-colony stimulating factor (G-CSF) (300-450 Ig/day subcutaneously for 6 days) in addition to cefotaxime plus dexamethasone (9-12 g/day for 10 days and 16 mg/day for 3 days iv, respectively). Patients recovered without evident sequelae in all cases but one (with bilateral hearing deficit). No adverse event was recorded. Improvement of inflammation indices in the cerebrospinal fluid was rapid. The most rapid improvement was seen in glucose concentration, which returned to normal ranges within 24-48 h of treatment. In this study G-CSF administration appeared to be safe and effective; further controlled clinical trials are justified.