Purpose To compare diffusion‐weighted imaging (DWI) findings and the apparent diffusion coefficient (ADC) values of pancreatic cancer (PC), mass‐forming focal pancreatitis (FP), and the normal pancreas. Materials and Methods DWI (b = 0 and 600 seconds/mm2) findings of 14 patients with mass‐forming FP proven by histopathology and or clinical follow‐up, 10 patients with histopathologically‐proven PC, and 14 subjects with normal pancreatic exocrine function and normal imaging findings were retrospectively evaluated. ADC values of the masses, the remaining pancreas, and the normal pancreas were measured. Results On b = 600 seconds/mm2 DWI, mass‐forming FP was visually indistinguishable from the remaining pancreas whereas PC was hyperintense relative to the remaining pancreas. The mean ADC value of PC (1.46 ± 0.18 mm2/second) was significantly lower than the remaining pancreas (2.11 ± 0.32 × 10–3 mm2/second; P < 0.0001), mass‐forming FP (2.09 ± 0.18 × 10–3 mm2/second; P < 0.0001), and pancreatic gland in the control group (1.78 ± 0.07 × 10–3 mm2/second; P < 0.0005). There was no significant difference of ADC values between the mass‐forming focal pancreatitis and the remaining pancreas (2.03 ± 0.2 × 10–3 mm2/second; P > 0.05). Conclusion Differences on DWI may help to differentiate PC, mass‐forming FP, and normal pancreas from each other. J. Magn. Reson. Imaging 2009;29:350–356. © 2009 Wiley‐Liss, Inc.