The authors report a case of metastases from a carcinoma of prostate producing mediastinal adenopathy with compression. The clinical presentation was unusual as this is an unusual area for lymphadenopathy and an abnormal lymphatic pattern was invoked as a possible cause or that the lymphatic channels communicating with these nodes had an abnormal thoracic duct. The aetiological diagnosis was facilitated by the presence of a specific prostatic antigen on the lymph node biopsy which allowed one to use an effective androgen suppression therapy.