In addition to mucositis and myelotoxicity as well known early reactions after radiotherapy or radiochemotherapy in advanced head and neck tumors, late toxicity following treatment is an often underestimated problem. Between 1992 and 1995, 68 patients with advanced oro- and hypopharyngeal tumors were treated primarily with accelerated concomitant boost radiochemotherapy (total dose irradiations of 66 Gy and carboplatin as chemotherapy). Ninety-three per cent of the patients had stage IV disease according to the UICC-TNM classification. Monitoring of follow-up included late toxicity with special attention given to laryngeal edema. In 37 patients (54%) edema of the larynx as a late complication of radiochemotherapy was observed by clinical investigation and CT scan. The median onset of laryngeal edema was found 121 days after completion of therapy, with a median time of observation of 250 days. Observations in these patients demonstrated the chronic character of this edema. An increase in the laryngeal edema in 5 cases resulted in tracheostomy. Laryngeal edema in 10 patients was associated with recurrence of tumor. These results show that after xerostomia laryngeal edema is the main late toxicity in the head and neck after radiochemotherapy and should lead to further investigations to exclude possible recurrent tumor.