The aim of this study was to compare tolerance of a nitrosurea-based regime with 'standard' therapy of vincristine (VCR) and carboplatin for low-grade gliomas. Ten children with low-grade gliomas received second line therapy consisting of thioguanine, procarbazine, CCNU and vincristine (TPCV). Two groups were identified, i.e. patients who had either experienced significant toxicity with carboplatin (reaction group) or had re-growth of their tumor (re-growth group) following first line therapy. Patients were evaluated for toxicity. Data was available on nine patients. Patients in the reaction group completed a mean of 3 cycles of TPCV (range 2-4). One patient stopped after 2 cycles of TPCV due to tumor progression and died 3 months later and one remained on therapy at the time of analysis. Patients in the re-growth group received a mean of 5.5 cycles of TPCV (range 4-8). Treatment was discontinued in one patient after 4 cycles due to hematological toxicity, one experienced tumor progression after 4 cycles and one stopped after 6 cycles because of neurological toxicity. There was no difference in the incidence of grade 3/4 neutropenia or thrombocytopenia, transfusion requirements or delays in chemotherapy between TPCV and VCR/carboplatin in either group. There were no serious infections or toxic deaths. Seven of nine patients had stable disease at a mean of 13 months of follow up. TPCV therapy is a well-tolerated regime with comparable bone marrow toxicity to VCR/carboplatin. Significant disease stabilization was observed with TPCV and hence this regime may be used as second line therapy.