EST 5275 is a phase II and III study of fluorouracil plus streptozocin (5-FU plus STZ) or doxorubicin in patients with measurable progressive carcinoid tumor. Among one hundred seventy-two cases with no prior chemotherapy and no heart disease, the response rate was 22% for 5-FU plus STZ and 21% for doxorubicin, while the median response duration and median survival were 31 weeks and 64 weeks for the combination and 26 weeks and 48 weeks for doxorubicin. Thirty-three patients who failed 5-FU plus STZ crossed over to doxorubicin and achieved an 18% response. Of the thirty-five patients who failed on doxorubicin, 29% responded to 5-FU plus STZ. Hematologic toxicity was similar for both treatments; however, the 5-FU plus STZ patients experienced more vomiting but acceptable renal toxicity. Both chemotherapy regimens have antitumor activity in carcinoid tumors.