20 g lactose load test, BHT and LTT done simultaneously were examined in 32 Crohn's disease patients and 51 healthy volunteers. Hypolactasia frequency were examined. A rise in hydrogen concentration > 20 parts per million (ppm) above the base line during breath hydrogen test and maximum blood sugar rise during lactose tolerance test were considered to indicated Hypolactasia. High rates, 50% by BHT and 72.5% by LTT, of primary adult hypolactasia were found in healthy volunteers as previously reported. Higher rates, 83.3% by BHT and by LTT (p < 0.05), were observed in Crohn's disease patients. There were higher rates in small intestine type Crohn's disease (91.6% by BHT, 92.3% by LTT) compare with healthy volunteers but no difference were found with large intestine type Crohn's disease.