We prospectively looked at the prognostic value of bronchoalveolar lavage (BAL) lymphocyte count in 98 patients with recently diagnosed (less than 4 months) untreated sarcoidosis. These 50 men and 48 women (mean age, 37.4) were followed up for a period of 6 to 60 months (mean, 25.6), and were clinically evaluated every three to six months with repeated chest roentgenograms and pulmonary function tests. Twenty-four patients required steroid treatment during the study period. The proportion of treated patients was not significantly higher in the group presenting a BAL lymphocyte count less than or equal to 30 percent at diagnosis than in the group with fewer lymphocytes (31.9 and 17.7 percent of total group respectively, p = 0.10). No significant change in TLC, FRC, FVC, FEV1 or DLCO was found at follow-up between the groups with or without an initial high lymphocyte count. In the treated group, BAL lymphocyte percent weakly correlated with the improvement of FEV1 and FVC while on steroid treatment (mean duration: 3.5 months): r = 0.41, p = 0.031 and r = 0.36, p = 0.05 respectively; no correlation was found with lung volumes and DCO. We conclude that BAL lymphocyte count at the time of diagnosis is not a helpful predictor of lung function deterioration in recently diagnosed sarcoidosis and is not very useful in predicting response to treatment.