Recurrent digital ulcers are manifestations of vascular disease in patients with systemic sclerosis (SSc). We report six patients with severe digital ulcers who were treated with bosentan administered p.o., 62.5–125 mg daily. The mean duration from the diagnosis of SSc to the initiation of bosentan was 9.5 years, and the observation period after bosentan administration was from 7 months to 4.5 years. In case 1, neither new digital ulcers nor Raynaud’s phenomenon developed for 4.5 years. In case 2, digital ulcers recurred after the discontinuation of bosentan; however, re-administration of bosentan lead to the improvement. In cases 3–5 with recurrent digital ulcers, no new lesions have developed. In these five patients, pain evaluated by visual analog scale was significantly reduced. In three patients, bosentan was discontinued because of severe liver dysfunction. These results suggest that bosentan is an effective treatment for refractory digital ulcers associated with SSc; however, liver function should be carefully monitored. Compared to the doses of bosentan used to treat pulmonary hypertension, relatively lower doses may effectively control painful digital ulcer/gangrene in patients with SSc.