Although the Crohn’s Disease Activity Index (CDAI) is often used to evaluate the disease activity in Crohn’s disease (CD), the number of liquid or soft stools cannot be precisely evaluated, and thus accurate scores cannot be calculated, in patients with enterostomy. Therefore, we created the modified CDAI (mCDAI), without the defecation frequency item from the CDAI, and examined its usefulness.Study participants comprised 9 patients with CD with enterostomy and 20 patients with CD without enterostomy. Correlations between the mCDAI and serum albumin (Alb) levels or C-reactive protein (CRP) levels were examined using regression analysis. Additionally, regression analyses were conducted in patients with CD without enterostomy to determine the Alb and CRP levels corresponding to the CDAI at its cutoff value for remission status (150). The obtained values were applied to the mCDAI regression equations to determine the equivalent mCDAI cutoff value.mCDAI and Alb levels were significantly negatively correlated (P < .0001). The mCDAI had a significant positive correlation with the CRP level and erythrocyte sedimentation rate (P = .0061 and P = .0133, respectively). From the regression analysis of patients with CD without enterostomy, the Alb and CRP levels equivalent to a CDAI of 150 were 3.85 g/dL and 0.62 mg/dL, respectively. When applying these values to the mCDAI regression formulas, the values of 113.8 and 115.2, respectively, were obtained. Thus, the cutoff value of the mCDAI indicating disease activity was estimated as 115.The mCDAI fully reflects the nutritional status and inflammatory response, and is convenient and useful for assessing disease activity over time, in patients with CD with enterostomy. A mCDAI score ≥ 115 indicates disease activity.