The quality of life questionnaire EORTC C30 with the head and neck specific module H&N35 has been validated in many languages and cultural settings, but the H&N35 module has not been formally translated to and validated in Danish. This validation was the purpose of the current study. In a cross sectional study 116 of 120 (97%) recurrence free head and neck cancer patients returned a valid questionnaire. The patients were attending follow up after radical radiotherapy (n=83), surgery (n=33) for cancer of the larynx (n=44), pharynx (n=34) or oral cavity (n=38). The previously described psychometric properties of the questionnaire were confirmed with the Danish translation. Nevertheless, there were some foreseeable problems with heavily skewed endpoints. Several scales of the questionnaire were sensitive to patient, tumour and treatment related factors: Good performance, high age, male gender, laryngeal cancer, low tumour stage and surgery correlated with a low score on the symptom scales or high score on the function scales. Symptom intensity increased with time since therapy in patients who had surgery and decreased in the irradiated patients. In conclusion, the current validation study confirmed the psychometric properties of the EORTC H&N35 questionnaire. The questionnaire detected correlations between clinical factors (performance status, gender, age, stage, site, time since therapy, treatment) and a large number of QoL factors. EORTC H&N35 in conjunction with EORTC C30 is a valid and informative tool in assessing quality of life, also in Danish head and neck cancer patients.