The diagnostic and therapeutic approach in patients with mediastinal masses (MM) treated at our institute between 1983 and 1993 was retrospectively reviewed. METHODS AND MATERIAL: 193 patients with MM (105 males and 88 females, average age 53, ranging from 16-81) underwent 223 interventions. Staging mediastinoscopies in lung cancer patients were ruled out. Long-term follow-up data were available in 123 of 162 cases with neoplastic MM (average follow-up time 5.5 years). Of all 223 surgical interventions 143 were diagnostic (53 parasternal mediastinotomies, 78 mediastinoscopies and 8 thoracoscopies) and 80 therapeutic (46 sternotomies and 34 posterolateral and a second half). The analysed period was splitted up in a first half (1983-1987) and second half (1988-1993) to study an eventual trend in the management of MM. RESULTS: The most frequent diagnoses were: thymoma (21%), malignant lymphoma (18%) and mediastinal sarcoidosis (14%). 43% of the MM were localized in the anterior, 46% in the middle and 7% in the posterior mediastinum. Thoracic pain, cough and dyspnoea represented the most common symptoms, leading to an invasive diagnostic procedure. 25% of the patients had no symptoms. The mortality and morbidity rate of all interventions was 3.4% and 18.7% respectively and concerned almost nerval injuries and postoperative respiratory failure. The percentage of direct tumor excisions increased from 21% during the first half of the period to 40% during the second half of the period, whereas diagnostic surgical interventions decreased from 57% to 44%. The percentage of total excisions after previous surgical biopsies decreased from 22% to 16%. In spite of the introduction of high resolution CT scan and MRI techniques during this time period no significant change in the use of presurgical diagnostic procedures was obvious. Fine needle biopsies and bronchoscopies were performed less frequent in the second half in comparison to the first half (11%, 7%, 29%, 13% respectively). From 123 patients with neoplastic disease data were available for long-term results. 35 had benign and 83 malignant histologies, in five cases dignity was unclear. 54% of these patients were disease-free at follow-up time, 10% had local recurrency or distant metastasis and 37% died during the observed time period. CONCLUSIONS: Surgical biopsy seems to remain the most important investigation for a successful interdisciplinary approach to MM. Overall morbidity and mortality rate of mediastinal surgery might appear remarkable but has to be related to the favorous long-term results after different individual treatment modalities in patients with mediastinal masses.