Background: Stereotactic body radiation therapy (SBRT) is a standard option for re-irradiation of recurrent or second primary cancers of the head and neck. We conducted performed a phase I clinical trial to establish a maximum tolerated dose of SBRT with concurrent cisplatin. We previously reported our safety data, and now present our secondary disease control endpoints. Methods: Major inclusion criteria were recurrence of previous squamous cell carcinoma of the head and neck in patients who had previously undergone radiotherapy to doses ≥ 45 Gy to the area of recurrence, ≥ 6 months prior to enrollment, and who were medically unfit for surgery, deemed unresectable, or refused surgery. Patients were treated with radiation therapy every other day for five fractions at three dose levels: 30 Gy, 35 Gy, and 40 Gy. Cisplatin was given prior to every SBRT fraction at a dose of 15 mg/m². Secondary end points reported herein are locoregional control (LRC), freedom from distant metastasis (FFDM), and overall survival (OS). Results: Twenty patients were enrolled and of those 18 patients were evaluable for secondary endpoints. Nine patients had a primary tumor in the oropharynx, four patients in the oral cavity, three in the neck, one in the larynx, and one simultaneously in the larynx and neck. All patients received the planned dose of Cisplatin. Five patients received a radiation dose of 30 Gy, three patients received a dose of 35 Gy, and 9 patients received a dose of 40 Gy. Median gross tumor volume (GTV) was 11.725 cm³. With a median follow up of 9 months the 1-year OS was 38.9%. LRC at 1 year was 45.7% and FFDM at 1 year was 87.8%. There was a trend to improved OS with increasing SBRT dose, 40 Gy vs < 40 Gy (p = 0.08). There was an improved 1-year OS with a GTV ≤11.725 cm³ of 77.8% vs 0% for tumors > 11.725 cm³ (p < 0.001). For patients with a GTV < 11.725 cm³ who received 40 Gy the 1 year OS was 100% compared with 0% for tumors larger than 11.725 cm³. Conclusions: For patients with previously radiated locally or regionally recurrent head and neck cancer, SBRT up to 40 Gy given concurrently with cisplatin provides reasonable locoregional control and overall survival for patients with smaller tumors. Further evaluation in prospective trials is warranted. Clinical trial information: NCT02158234