In the early 1990s, when conventional radiotherapy (RT) was the standard of care in patients with locally advanced head and neck squamous cell carcinoma (HNSCC), two main options were being tested to improve the efficacy and the therapeutic ratio of RT. The first approach evaluated the effect of adding chemotherapy (CT) simultaneously to RT (RT-CT), while the second approach assessed the effect of modified fractionated RT. To answer these two questions, in 1994, the French Group for Head and Neck Oncology Radiotherapy (GORTEC) initiated two randomized trials. A total of 494 patients were entered in these two parallel phase III multicenter trials comparing conventional RT (70 Gy in 35 fractions) either with concomitant RT-CT (226 patients; 70 Gy in 35 fractions with three cycles of a 4-day regimen comprising carboplatin and 5-fluorouracil [5FU]) or with very accelerated RT (268 patients) delivering 64 Gy in 3 weeks. The 5-year overall survival (OS), specific disease-free survival (DFS), and local-regional control rates were improved in favor of simultaneous RT-CT, whereas local-regional control was significantly improved with accelerated RT, along with a marginal effect on OS and DFS. This increased antitumor efficacy was in both cases associated with a marked increase in acute RT-induced toxicity, which was more pronounced with accelerated RT, whereas late effects were marginally increased with the addition of CT and not influenced by accelerated RT. We conclude that both concomitant RT-CT and accelerated RT improved tumor control rates, as compared to conventional RT, along with increased but manageable toxicity. The two regimens are currently being tested in an ongoing randomized study and also being compared to moderately accelerated RT and concomitant CT.