On the basis of 112 cases of pulmonary or mediastinal neoplasms observed during the treatment or follow-up of 952 carcinomas of the pharynx and larynx, the authors study in detail 45 cases of metastases. They draw the following conclusions:--metastases present clinically relatively early in the treated course of pharyngolaryngeal carcinomas: 85% before 18 months.--cannonball lesions are the commonest endo-thoracic clinical metastases: 6 out of 10.--carcinomas of the hypopharynx are at the origin of 2/3 of cannonball lesions (alpha less than or equal to 0.02) and 1/4 of mediastinal lymphadenopathies and pleural effusions.--endolaryngeal carcinomas are rarely at the origin of cannonball lesions and are associated almost exclusively with mediastinal lymphadenopathies and pleural effusions (alpha less than 0.001). The influence of the size of the primary tumour, of lymph node involvement, of capsular rupture and of failure to eliminate all malignant cells from the primary lesion are considered and discussed.