Purpose: The present study aimed to examine the characteristics, outcomes, and problems related to surgery for acute abdomen in adult patients with severe motor and intellectual disabilities (MID). Methods: The clinical records of 35 adult patients with severe MID who received emergency surgery for acute abdomen between 2011 and 2020 were reviewed. Results: The median duration from onset to surgery was 48 hours. There were 2 cases of in-hospital mortality (5.7%), and all the patients underwent surgery more than 72 hours after onset. The in-hospital mortality rate was significantly higher in patients who received surgery later than 72 hours after onset. Bowel obstruction was the most common disease among the acute abdomen cases (71.4%) and most often involved volvulus of the small bowel and cecum. Of the patients with bowel obstruction with severe MID, 72.0% had abdominal distention, 16.0% had abdominal pain, and 4.0% had vomiting.The median duration from onset to surgery was significantly longer in the patients with bowel obstruction with severe MID than in those without severe MID (24 hours vs. 16 hours). Conclusion Acute abdomen in patients with severe MID was often due to bowel obstruction caused by volvulus. Because patients with severe MID have few symptoms, they are susceptible to adverse surgical outcomes associated with a prolonged duration from onset to surgery.