Extragonadal germ cell tumors may have a worse prognosis than germ cell tumors of gonadal origin, even when tumor bulk and extent of dissemination are equal. Primary retroperitoneal pure choriocarcinoma is one of the least common subgroups of the extragonadal germ cell tumors and has previously appeared to have the worst prognosis. Two new case reports on the treatment and follow-up of two patients with primary retroperitoneal pure choriocarcinoma are discussed. Both patients are disease-free at 24 and 81 months, respectively. After aggressive primary multiagent drug therapy for primary retroperitoneal pure choriocarcinoma, a favorable prognosis may be anticipated.