Induction chemotherapy-based larynx preservation protocols use chemotherapy to select exclusively patients with 'chemosensitive' tumors for a nonsurgical treatment with radiation therapy. This study on pyriform sinus squamous cell carcinoma (SCC) is interested in the oncological outcome of treatment based on radiation therapy when offered to patients with tumors responding to induction chemotherapy. This was a retrospective cohort study. The cohort included good responders to induction chemotherapy, subsequently treated with definite radiation therapy (with or without concomitant chemotherapy) for pyriform sinus SCC, in a tertiary referral cancer center. The primary endpoints were overall, laryngectomy-free and disease-free survival and the secondary endpoints were analysis of treatment failures and possibilities of salvage treatment. Forty-two patients fulfilled the inclusion criteria and were retained for analysis; 7 % were stage II (3/42), 48 % stage III (20/42) and 45 % stage IV (19/42). At 1, 3 and 5 years, the overall survival was 95 % (40/42), 74 % (31/42), and 60 % (SE ≈ 0.08), respectively. For the same intervals, the laryngectomy-free survival was 90 % (38/42), 69 % (29/42) and 50 % (SE ≈ 0.08), respectively. The estimated 5-year disease-free survival was also 50 %. Disease-free survival was significantly better for N0 patients. There was a 28 % recurrence rate, mainly in the primary tumor site (9/11), with or without simultaneous nodal recurrence. Interestingly, more than one-third of all oncologic failures occurred beyond the first 3 years of follow-up. Salvage treatment was not possible or definitely inefficient in at least 2/3 of all recurrences. In candidates for larynx preservation for a pyriform sinus SCC, good response to induction chemotherapy followed by definite radiation therapy seems to be associated with a more favorable prognosis. Nevertheless, in case of locoregional recurrence the possibilities for efficient salvage treatment are limited.