MPORTANCE Digital ulcers in patients with systemic sclerosis are associated with pain and poor quality of life. Endothelin-1 promotes vasculopathy in systemic sclerosis after macitentan, an endothelin-1 blocker. OBJECTIVE To evaluate the efficacy of macitentan in reducing the number of new digital ulcers in patients with systemic sclerosis. DESIGN, SETTING, AND PARTICIPANTS Two international, randomized, double-blind, placebo-controlled trials (DUAL-1, DUAL-2) were conducted between January 2012 and February 2014. Participants were patients with systemic sclerosis and active digital ulcers at baseline. Target enrollment for each study was 285 patients. INTERVENTIONS Patients were randomized (1:1:1) to receive oral doses of 3 mg of macitentan, 10 mg of macitentan, or placebo once daily and stratified according to number of digital ulcers at baseline (3 or >3). MAIN OUTCOMES AND MEASURES The primary outcome for each trial was the cumulative number of new digital ulcers from baseline to week 16. Treatment effect was expressed as the ratio between treatment groups. RESULTS In DUAL-1, among 289 randomized patients (mean age 51.2 years ; 85.8% women), 226 completed the study. The adjusted mean number of new digital ulcers per patient over 16 weeks was 0.94 in the 3-mg macitentan group (n = 95) and 1.08 in the 10-mg macitentan group (n = 97) compared with 0.85 in the placebo group (n = 97) (absolute difference, 0.09 [95% CI, −0.37 to 0.54] for 3 mg of macitentan vs placebo and 0.23 [−0.27 to 0.72] for 10 mg of macitentan vs placebo). Among 265 patients randomized in DUAL-2 (mean age 49.6 years ; 81.9% women), 216 completed the study. In DUAL- 2, the adjusted mean number of new digital ulcers was 1.44 in the 3-mg macitentan group (n = 88) and 1.46 in the 10-mg macitentan group (n = 88) compared with 1.21 in the placebo group (n = 89) (absolute difference, 0.23 [95% CI, −0.35 to 0.82] for 3 mg of macitentan vs placebo and 0.25 [95% CI, −0.34 to 0.84] for 10 mg of macitentan vs placebo). Adverse events more frequently associated with macitentan than with placebo were headache, peripheral edema, skin ulcer, anemia, upper respiratory tract infection, diarrhea, and nasopharyngitis. CONCLUSIONS AND RELEVANCE Among patients with systemic sclerosis and active ischemic digital ulcers, treatment with macitentan did not reduce new digital ulcers over 16 weeks. These results do not support the use of macitentan for the treatment of digital ulcers in this patient population.