Abstract： Objective To evaluate the ability of diffusion-weighted imaging (DWI)in differentiating pancreatic carcinoma from chronic lump type pancreatitis. Methods Totally 38 cases of pancreatic cancer, 9 cases of chronic lump type pancreatitis, 15 cases of normal patients underwent DWI. DWI with b value＝0, 500, 1 000 s/mm2 was performed twice. Apparent diffusion coefficient (ADC) was measured by analysis of imagines of ADC. Results The mean ADC value of 38 subjects with pancreatic carcinoma was (1.411± 0.101)×10-3 mm2/sec, the mean ADC value of 9 subjects with lump type pancreatitis was (1.053±0.113) ×10-3 mm2/sec, and the mean ADC value of normal pancreas subjects was (1.245±0.112)×10-3 mm2/s. The difference between the three groups were statistically significant (P＜0.05). Conclusions DWI may have the clinical potential to differentiate chronic lump type pancreatitis from pancreatic carcinoma.