Thirty-nine sarcoidosis patients with pulmonary infiltrations (stage II) of less than 5 years duration and not treated earlier with corticosteroids were randomly allocated for treatment with methylprednisolone for 7 months or for observation without therapy. Every other treated patient was given the drugs daily and every other followed an alternate-day regimen. After 7 months the chest radiographic finding, the forced vital capacity and the diffusion capacity for carbon monoxide were superior in the treated group. There was no difference between the two drug regimens. After 24 and 48 months no statistically significant differences between the untreated and the treated groups were found.