ABSTRACT. To determine the frequency of splenic involvement in sarcoidosis, fine-needle aspiration biopsies of the spleen have been performed on 77 patients with verified sarcoidosis. Spleen size was normal in 71 patients and enlarged in 6. Splenic sarcoidosis was demonstrated in 53% of all patients, and in 67 % of those with and in 47 % of those without known extrathoracic manifestations. No complications occurred with this simple bedside procedure. In sarcoidosis, fine-needle aspiration biopsy of the spleen is a valuable diagnostic tool, especially when visible or palpable lesions are absent. Its use is recommended before the use of mediastinoscopy, bronchoscopy, lung biopsy or laparoscopy.