Tuberculosis is a frequent cause of prolonged fever. Mediastinal lymph node enlargement is an uncommon feature of intrathoracic tuberculosis in adults. The authors present the case of a 64 year old man who developed prolonged fever and was admitted to Clinical Hospital of Infectious Diseases and Pneumophtisiology Dr. Victor Babeş Timişoara during 06.04-15.04.2009. Diagnosis of mediastinal lymph node tuberculosis was established only after axillary thoracotomy and biopsy of tumoral mass, although the first results obtained after mediastinoscopy were negative. Dynamics of biological features, diagnostic pitfalls, differential diagnosis difficulties and peculiar aspects of evolution are presented. Mediastinal tuberculous adenopathy, without associated pulmonary involvement is a rare form of presentation among adults, generally evolving with sustained fever. Diagnosis of mediastinal tuberculosis is difficult due to non-specific clinical aspects and lack of characteristic radiographic features and so invasive diagnostic procedures gain importance (mediastinoscopy and biopsy).