Objective To investigate the taste alteration caused by radiotherapy and its relationship with nutritional status in head and neck cancer patients during and after radiotherapy.Methods From March to November 2017,172 patients with head and neck cancer receiving radiotherapy were recruited from Beijing Cancer Hospital including 86 patients completing all follow up visits.Chemotherapy-induced Taste Alteration scale was used to evaluate radiotherapy-induced taste alteration and the Patient-generated subjective global assessment (PGSGA) was used for nutrition evaluation at baseline,mid-treatment,post-treatment and 1-2 months after radiotherapy (follow-up).Generalized estimating equations was applied to analyze the influencing factors of taste alteration and its relationship with nutritional status.Results The incidence of taste alteration were 9.3％,84.9％,94.2％ and 77.9％ respectively at baseline,mid-treatment,post-treatment and 1-2 months after radiotherapy (follow-up).Taste alteration score increased with the increase of radiation dose,reached the highest at the posttreatment and decreased at follow-up visit which was still higher than the score at baseline.PG-SGA score increased with the increase of radiation dose.The incidence of severe malnutrition after radiotherapy was 95.3％,decreased to 45.3％ at follow up visit.Nutritional status was closely related to taste alteration.Total radiation dose and concurrent chemotherapy were the influencing factors of taste alteration.Conclusions The taste of patients with head and neck cancer is affected by radiotherapy.As radiotherapy continues,the taste alteration aggravates and PG-SGA score increases gradually,thus malnutrition becomes a prominent problem.Such effect will persist for a period of time after radiotherapy,which should be paid attention and interventions should be conducted to prevent or reduce this effect,in order that the lasting of malnutrition induced by taste alteration can be avoided.