This is the final report of the Phase I Protocol for the initial clinical study of Multiple Dose WR-2721 with radiotherapy (RTOG 80-02). The essential object of the study was to determine the highest dose of WR-2721 that could be given daily for the greatest number of weeks 15 to 30 minutes before conventional radiation treatment schedules. Eighty-four patients were entered into various dose levels. The major and dose-limiting toxicities were emesis, hypotension and malaise. The latter symptom was characterized by increasing weakness, fatigability, and ill-feeling. The maximum tolerated dose (MTD) established by this study is 340 mg/m2 given 4 days a week (excepting Wednesday) for 5 weeks. The drug is delivered intravenously in 7 minutes. There were no long-term blood chemistry changes. There were no deaths due to the administration of the radioprotector.