Twenty-two consecutive patients with recurrent malignant brain tumors after radiation therapy and systemic combination chemotherapy with BCNU and vincristine, four of whom were not evaluable due to early death, were treated with etoposide (VP-16-213) (50-100 mg/m2 for five days every three weeks). Response, defined as improvement in both clinical examination and computed tomography scan in absence of glucocorticoids dosage increase, was observed in three (17%) of 18 evaluable patients, lasting greater than 21, seven, and two months, respectively. Six additional patients had stable disease for greater than 10, seven, four, four, three, and two months: all of them had improvement of clinical symptoms but no variation in their scans. Overall median survival from the start of VP-16-213 was 4.5 months (range, 1-23 + months), whereas patients with response or stable disease had a median survival of eight months. Overall, treatment was well tolerated. In 10 patients concomitant plasma and cerebrospinal fluid samples were evaluated with a high-performance liquid chromatographic method for drug assay. The concentration of VP-16-213 in cerebrospinal fluid was less than 1% that found in plasma, even in the two patients with response. The activity of etoposide in patients with malignant, lomustine-vincristine-resistant brain tumors suggests an interesting potential use for this drug.