Background: Cancer patients face considerable financial burden, but few studies have explored associations between radiation therapy (RT) and financial toxicity. This study assessed financial toxicity, patient-reported outcomes, and attitudes/perspectives on the role of cost in treatment decisions. Methods: In a prospective, survey-based, longitudinal study (NCT3506451), eligible patients were adults with newly diagnosed non-metastatic head and neck cancer (HNC) undergoing RT as part of their definitive cancer treatment. Surveys collected demographics, cancer details, the COmprehensive Score for financial Toxicity (COST) score to measure financial toxicity, and patient attitudes regarding cost conversations. Results: 60 patients were enrolled (2019-2021), and 58 completed the baseline survey prior to the start of RT. Most were white (75.9%) and non-Hispanic (98.1%). Median age was 61 (range 42-86). Most were married or in long term partnerships (67.0%), had completed at least some college (70.7%), and had employer sponsored private insurance (55.2%). Half were working at least part time, and most earned > $60,000/yr (55.4%). Oropharynx (48.3%) was the most common disease site; almost half (48.1%) received concurrent chemotherapy. Median baseline COST score was 25 (range 0-44), indicating borderline financial toxicity. 37.7% had reduced spending on leisure items, and 30.9% had reduced spending on basics like food or clothing to pay for cancer care. 10.5% had skipped doses of medications to make them last longer, and 21.1% had not filled a prescription because it was too expensive. 19.6% had borrowed money, and 36.4% had used either all or part of their savings (or had no savings at all) to pay for care. Of those employed at diagnosis, 38.9% took extended leave or reduced hours to part time. 25.9% felt their treatment costs/financial situation should be a factor in treatment decisions. 50.8% wanted the less costly treatment, assuming equal effectiveness. 46.6% felt they should receive cost information from their doctor, and 63.8% wanted a financial assistance counselor or social worker to provide cost information. 46.6% felt that discussing their costs would make them feel more involved in their care. While 43.1% felt that talking about cancer-related costs would reduce their anxiety, 36.2% felt it would increase their anxiety. The majority (63.8%) had little or no understanding about the costs of their cancer care, and 69.0% felt that educational materials about costs would be helpful. Conclusions: Despite borderline baseline financial toxicity scores, some HNC patients had already made significant sacrifices in order to afford care before RT had even started. There was little baseline knowledge of cancer costs and overall mixed attitudes toward cost conversation. Most patients felt that cost education would be helpful. Clinical trial information: NCT03506451