There are no guidelines regarding the treatment of pulmonary sarcoidosis. Generally, oral corticosteroids are considered the first-line treatment for symptomatic patients with pulmonary sarcoidosis. We report here two Japanese cases with pulmonary sarcoidosis who demonstrated sequential evolution from radiographic stage I to III within five years. Although these two cases had no symptoms, persistent, progressive pulmonary involvements were observed on chest X-ray. Considering the effectiveness of corticosteroids on patients with radiographic type II or III sarcoidosis reported by the British Thoracic Society, corticosteroid therapy might be a choice even in asymptomatic cases, if they demonstrate developing pulmonary involvement.