Zafirlukast, a competitive cysteinyl leukotriene receptor antagonist, is a new class of asthma medications. It has shown an adverse event profile similar to that of placebo. Herein, we present a 69-year-old female patient who suffered from general malaise, poor appetite, nausea and jaundice after 3 months of zafirlukast therapy for asthma. She had no past history of liver disease, nor history of alcoholism, herb medication, blood transfusion, acupuncture, tattoo or recent traveling history. Liver biochemistries revealed elevated serum alanine aminotransferase and aspartase aminotransferase levels up to 481 U/L and 212 U/L, respectively. Moreover, peak serum total bilirubin level was elevated to 34.8 mg/dL during admission. Serum viral hepatitis marker, antinuclear antibody, anti-mitochondrial antibody and anti-smooth muscle antibody were all negative. Her general condition and liver biochemistries improved gradually after zafirlukast was discontinued. Roussel Uclaf causality assessment for adverse drug reaction confirmed the diagnosis of drug-induced liver injury. This case reminds us that zafirlukast is a potentially hepato-toxic drug. If clinical manifestations of hepatitis develop, patients should be managed cautiously and closely monitored for liver biochemistries. If drug-induced hepatitis is suspected, medication should be discontinued immediately to prevent further liver injury.