Background: Are 6 cycles of once weekly DDP plus one cycle of 5-FU with concurrent HART superior to 2 cycles of MMC plus one cycle of 5-FU in terms of overall survival (OS) and metastases-free survival (MFS)? Methods: Eligibility: Stage IV SCC of oro(OP)- and hypopharynx(HP), KFS of ≥80% stratified for sites, N-status, grading, hemoglobin and center. The HART schedule was reported elsewhere (V.Budach, JCO 23;2005). HART was applied concurrently with DDP/5-FU at 30mg/m² days 1,8,15,22,29,36 or MMC/5-FU at 10mg/m² day 1+36 and for both arms with 600mg/m² 5-FU days 1-5 as 120 hrs. c.i. TVD dose prescription was 72 Gy using 3D-conformal or IMRT-TP. 364 patients were analysed using an ITT principle for OS, MFS, progression-free survival (PFS) and loco-regional control (LRC). Hazard ratio (HR) calculations were adjusted for competing risk factors. Results: Median follow-up was 48 mos. for both arms. Mean age was 55.4 years, 83/17% were male/female and 100% stage IV patients (UICC 2002). 58.5%/41.5% of all patients suffered from OP- or HP cancer, respectively. The OS and MFS at 4 years for the DDP- versus MMC-arm was 42.1% vs. 38.8% (n.s.) and 67.3% vs. 56.6% (p=.05), respectively. The LRC and PFS for the DDP versus MMC-arm was 58.6% vs. 57.2% (n.s.) and 46.4% vs. 38.7% (n.s.). Seven items recorded for acute toxicity and 9 for late morbidity showed no significant differences between the treatment arms except for creatinine for the DDP-arm (p < 0.001) using nonparametric analyses of variances for repeated measurements. The overall compliance rates for RTX were 96%, DDP: 72%, 5-FU: 97%, MMC: 86%, respectively. Conclusions: This phase III trial first establishes level IB-evidence for a once weekly DDP chemoradiation regimen. For MFS at 4 yrs., DDP/5 FU-HART is superior to MMC/5 FU HART at equal levels of acute and late radiation sequelae for both treatment arms. No significant differences were seen yet for OS, PFS or LRC. Chemoradiation with weekly DDP/5-FU or MMC/5-FU shows excellent compliance rates and can easily compete with other concurrent chemo- or bio-radiation schedules including induction TPF followed by radiation.