The study sought to evaluate the response to cyclophosphamide (CPM) in hepatoblastoma (HB). Patients with a refractory or relapsing HB after first-line therapy as per SIOPEL 2 and 3 protocols were eligible. All patients were to receive two courses of CPM 2 g/m(2) on days 1 and 2 at 3-week intervals. Eighteen patients were included; 17 were evaluable for response. Prior treatment was cisplatinum alone (1 patient) or cisplatinum-carboplatin-doxorubicin (17 patients). The disease status at the beginning of CPM was: progressive during first-line treatment (10 patients), persistent unresectable disease at the end of the protocol (2 patients), relapse (6 patients). Tumour response was partial response (1 patient), stable disease (1 patient), progressive disease (15 patients) and not evaluable in one. All patients died, 17 of progressive disease and one of surgery complications. The low response rate (1/17) led the SIOPEL group to conclude that single-agent CPM is not effective for the treatment of relapsing or refractory HB.