Background: The EPO-VAC protocol was initiated to study 1) the efficacy of adding a cisplatin regimen (EPO) to VAC alone (the previous standard of care) and 2) the effect of replacing bleomycin with etoposide in the treatment of pediatric endodermal sinus tumors., Methods: The eligibility requirements for entry included age <21 years at diagnosis, diagnosis of a primary gonadal or extragonadal tumor (excluding central nervous system tumors and stage I testicular tumors), and histological confirmation of endodermal sinus tumor. Children who met the eligibility criteria were treated with four courses of EPO (etoposide, cisplatin, vincristine) alternating with three courses of VAC (vincristine, dactinomycin, and cyclophosphamide)., Results: Eleven children were entered on the protocol. Six patients had extragonadal disease, five patients had ovarian primaries. Seven patients had low-stage tumor (I or II) and four had advanced-stage tumor (III or IV). Three of six evaluable patients attained a complete response at 21 weeks. Three patients with a residual soft tissue mass at restaging underwent further therapy. No patient has relapsed after a median of 51 (range 14-88) months of follow-up., Conclusions: The results of this protocol suggests that a cisplatin-containing regimen that lacks bleomycin is active in childhood endodermal sinus tumors.