Abstract: Objective: To explore CT features of autoimmune pancreatitis(AIP) at initial diagnosis and during follow-up period. Materials and Methods: Clinical and CT features were retrospectively analyzed in 6 patients with AIP, and the abdominal CT examinations included CT before and after steriod treatment, CT in the periods of disease recurrence, and CT in the routine follow-up. Results: At initial diagnosis, pancreatic parenchyma showed diffuse enlargement in 5 patients and focal enlargement in 1 patient, and gradual enhancement in the involved pancreatic parenchyma was seen. Hypo-attenuation rim was seen in 2 patients, pancreatic duct within the diseased pancreas was not visible in 6 patients, and intra-pancreatic bile duct wall thickening was seen in 6 patients. On the abdominal CT after steroid treatment, the size of the diseased pancreas decreased gradually in 6 patients with recheck and 4 patients with routine follow-up CT, the atrophy of the pancreatic parenchyma and progressive enhancement were seen in 2 patients. The hypo-attenuation rim around the pancreas disappeared in 2 patients. The diameter of the narrowed bile duct returned to normal in 6 patients. The pancreatic lesions recurred in 3 patients, diffuse enlargement of the pancreas, and focal enlargement in the pancreatic head was shown in 1 patient accompanying the atrophy of the pancreatic body and tail. The pancreatic duct was not visible in 3 patients. A pseudocyst in the front of pancreas was found in 1 patient. Conclusion: CT features of AIP were similar at initial diagnosis and disease recurrence, the main findings included diffuse or focal enlargement of the pancreas and invisible pancreatic duct; the pancreatic parenchyma decreased gradually, even atrophied, may be seen during follow-up after steroid treatment.