Sarcoidosis is characterised by a T-helper cell-alveolitis. Phenotyping of T-cells of bronchoalveolar lavage (BAL) and of peripheral blood was performed with antibodies directed against naive T-cells (CD45RA+), memory T-cells (CD45R0+), alpha beta T-cell antigen receptor (TCR) bearing cells and gamma delta T-cell antigen receptor bearing cells in 11 patients with active sarcoidosis, 5 patients with inactive sarcoidosis, 5 patients with idiopathic pulmonary fibrosis (IPF), and in control individuals (7 for BAL and 21 for peripheral blood). In peripheral blood one third of sarcoidosis patients exhibited increased (< 12%) numbers of TCR gamma delta+ cells. The corresponding numbers of BAL were within the normal range. More than 95% of alveolar T-helper cells in sarcoidosis, in IPF, and in controls could be identified as memory T-cells (CD45R0+). In comparison to controls in the peripheral blood of sarcoidosis and IPF patients a small, not-significant shift towards memory T-cells was observed. The immunophenotypical markers evaluated in BAL and peripheral blood did not yield parameters for the clinical staging of the investigated diseases.