Abstract: 2-fluoro-2-deoxy-D-glucose (FDG) is the most widely used agent for imaging tumors with positron emission tomography (PET). However, diagnosis of malignant tumors with FDG PET can create a relatively high false positive ratios, which is based on the difficultly differentiating tumor from inflammation. Imaging choline metabolism with PET can overcome some limitations of FDG PET and has clinical potential in tumors such as prostate cancer, brain tumors and bladder cancer with a significant advantage over FDG PET. The basic principle for imaging choline metabolism with PET, PET tracers for imaging choline metabolism and their applications are summarized.