Objective: The purpose of this paper is to present patient reported outcomes (PRO) of oral function and toxicity in head and neck cancer (HNC) patients and the clinical oral conditions affecting diet and maintenance of body weight during and following cancer therapy. Study design: Patients with HNC were evaluated during and following cancer therapy. Oral conditions affecting taste and oral diet, including taste and smell function were assessed. Results: The participating patients reported appetite decline and taste loss in 50% of patients during and in 62.5% following treatment. Decreased food intake and altered food choice were reported as severe by 50% of patients. Throat and mouth pain affected 67% of acute and 42% of post-treatment patients. The spicy perception of capsaicin was reported to have severe impact for 80% of acute and 70% of post-treatment patients. Bitter taste perception affected oral diet either often or all the time in 33% of acute and in 83% of post-treatment patients. Weight loss occurred in 5% during treatment and in 12% post-treatment. Conclusions: This is the first report of clinical oral function including taste and smell testing, saliva production and patient reported outcomes. Oral complications including mucositis and saliva affect taste change throughout cancer treatment and in the first two years of survivorship. This study provides initial suggestions that may guide diet and food intake and in product development for HNC patients.