Severe acute respiratory syndrome (SARS) is a newly emerging infectious disease. To describe the hepatic injury caused by this disease, we report the sequential changes of serum transaminase in probable SARS patients during a hospital outbreak in southern Taiwan. From April to June, 2003, 52 probable SARS patients were hospitalized. Serial serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were retrospectively analyzed and hepatitis B surface antigen (HBsAg) was also evaluated to correlate with the progression of this disease. Fifty-three percent of the patients had abnormal liver function during hospitalization. More than 70% of abnormal transaminase levels were mildly elevated. Most elevated levels were noted during the second week after onset of fever. Neither transaminase elevation nor HBsAg was related to the prognosis of SARS, and only advanced age was an independent predictor of poor outcome. Our study suggested that coronavirus causing SARS might induce liver damage.