Background: Small intestinal bacterial overgrowth (SIBO) results in nutrient malabsorption and malnutrition, thereby increasing the morbidity and mortality in systemic sclerosis (SSc) patients. Objectives: To evaluate the prevalence and associated factors of SIBO in SSc patients. Method: A cross-sectional study was conducted between July 2015 and January 2016 in SSc patients over 18, using the glucose H 2 /CH 4 breath test to evaluate SIBO. Results: Eighty-nine SSc patients (30 male and 59 female) underwent the glucose H 2 / CH 4 breath test. The mean age was 54.4. Twelve participants were positive for the glucose H 2 /CH 4 breath test, yielding a SIBO prevalence of 13.5% (95% CI 7.2-22.4) among SSc patients. A multivariate analysis revealed that duration of disease >5 years was significantly associated with SIBO (adjusted odds ratio 9.38; 95% CI 1.09-80.47). Conclusion: The prevalence of SIBO, using the glucose H 2 /CH 4 breath test, is not common among Thai SSc patients. However, a positive result was associated with longer duration of disease. K E Y W O R D S hydrogen breath test, scleroderma, small intestinal bacterial overgrowth, systemic sclerosis | CON CLUS IONThe prevalence of SIBO as detected by the glucose H 2 /CH 4 breath test was not common among Thai SSc patients. When present, SIBO was associated with a longer duration of disease. ACK N OWLED G EM ENTSThe authors thank the patients for their participation, the Faculty of Medicine and the Scleroderma Research Group, Khon Kaen University for their support, The Gastroenterological Association of Thailand for its support, and Mr. Bryan Roderick Hamman for assistance with the English-language presentation under the aegis of the Publication