Objective To investigate the value of magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) in the diagnosis of autoimmune pancreatitis (AIP). Methods Clinical data of 11 patients pathologically diagnosed with AIP in Sun Yat-sen Memorial Hospital, Sun Yat-sen University from January 2013 to June 2014 were analyzed retrospectively. There were 7 males and 4 females with a mean age of (54±15) years old. The informed consents of all patients were obtained and local ethical committee approval had been received. Apparent diffusion coefifcient (ADC) of the pancreatic lesions was measured by MRI scan, multiphase dynamic enhanced scan and DWI. The imaging features of AIP by MRI and DWI were observed. Results The AIP lesions displayed iso-or slightly hypo-intense signal on T1WI and slightly hyper-intense signal on T2WI by MRI and continuous gradual enhancement by multiphase dynamic enhanced scan. The average ADC of the lesions by DWI was (1.09±0.09)×10-3 mm2/s and the pancreatic lesions displayed high signal. Diffusely swelling pancreas with plump shape, sausage-like appearance was observed in 7 cases. Local mass were observed at the pancreatic head in 3 cases. Mass in the pancreatic body and tail was observed in 1 case. Capsule-like ring-like shadow was observed around the pancreas in 6 cases by MRI and iso-or slightly hypo-intense signal on T1WI and slightly lower-or hyper-intense signal on T2WI were observed. No enhancement or hypo-enhancement was observed in arterial phase by multiphase dynamic enhanced scan. Delayed enhancement was observed in delayed phase. The enhancement degree was mildly lower than that of pancreatic parenchyma. Multiple enlarged lymph nodes were observed around the pancreas and at the retroperitoneum in 4 cases. Conclusions MRI is useful for the diagnosis of AIP. The dynamic enhanced scan and DWI ifndings can be used as the direct images for diagnosing AIP and have a high clinical reference value.