BACKGROUND Gallbladder perforation and gastrointestinal fistula are rare but serious complications of severe acute pancreatitis (SAP). However, neither spontaneous gallbladder perforation nor cholecysto-colonic fistula has been reported in acalculous acute pancreatitis patients. METHODS A 31-year-old male presenting with epigastric pain was diagnosed with hypertriglyceridemia-related SAP. He suffered from multiorgan failure and was able to leave the intensive care unit on day 20. Three percutaneous drainage tubes were placed for profound exudation in the peripancreatic region and left paracolic sulcus. He developed spontaneous gallbladder perforation with symptoms of fever and right upper quadrant pain 1 mo after SAP onset and was stabilized by percutaneous drainage. Peripancreatic infection appeared 1 mo later and was treated with antibiotics but without satisfactory results. Then multiple colon fistulas, including a cholecysto-colonic fistula and a descending colon fistula, emerged 3 mo after the onset of SAP. Nephroscopy-assisted peripancreatic debridement and ileostomy were carried out immediately. The fistulas achieved spontaneous closure 7 mo later, and the patient recovered after cholecystectomy and ileostomy reduction. We presume that the causes of gallbladder perforation are poor bile drainage due to external pressure, pancreatic enzyme erosion, and ischemia. The possible causes of colon fistulas are pancreatic enzymes or infected necrosis erosion, ischemia, and iatrogenic injury. According to our experience, localized gallbladder perforation can be stabilized by percutaneous drainage. Pancreatic debridement and proximal colostomy followed by cholecystectomy are feasible and valid treatment options for cholecysto-colonic fistulas. CONCLUSIONS Gallbladder perforation and cholecysto-colonic fistula should be considered in acalculous SAP patients.