Background and aims Diarrhea was not uncommon in patients with coronavirus disease 2019 (COVID-19), but the significance remains undetermined. Methods This retrospective study included 157 diarrhea cases form 564 hospitalized COVID-19 patients who were admitted to Wuhan Union Hospital from January 20 to February 29, 2020. Clinical characteristics, the course and the outcome of patients with diarrhea were analyzed. The correlation between diarrhea and fecal presence of coronavirus was also determined. Results The overall morbidity of diarrhea was 27.8% (157/564) in COVID-19 patients. Among them, 38 cases presented only with diarrhea, and 119 cases in both diarrhea and respiratory symptoms. Patients with diarrhea and respiratory symptoms had higher levels of inflammatory activity, longer hospital stay (27.5 vs. 23.0 vs. 22.0 days, p = .029) and higher odds ratio of mortality (3.2 times and 2.2 times, respectively) than those with diarrhea only or respiratory symptoms only. However, patients with diarrhea had longer time from onset to admission (14.5 days vs. 11.0 days, p = .04), higher positive viral RNA in stool (80.0% vs. 52.4%, p = .016) than those with both diarrhea and respiratory symptoms. Conclusions Diarrhea caused by high enteric viral burden may lead to long course and poor outcome in COVID-19 patients. The patients with diarrhea and respiratory symptoms were prone to serious condition, and had worse outcomes. However, the patients with diarrhea alone showed mild illness but delayed health-seeking.