Background: colorectal cancer   is the second most common cause of cancer in women (9.2% of diagnoses) and the third most common in men (10.0%), it is the fourth most common cause of cancer death after lung, stomach, and liver cancer. Aim of the Work: the goal of this study was to elucidate the role of 18F-FDG PET-CT in evaluation of colorectal cancer. Patients and Methods: twenty five patients with histopathologically proven colorectal primary malignancy were evaluated for suspected local recurrence and metastasis. No age predilection and both sexes were included, clinical history, image follow-up, tumor markers, and pathological reports were reviewed for gold standard. Results: the final diagnosis of distant metastasis and/or local recurrence in post-therapeutic cancer colon was evident in 70% of our patient population with PET/CT sensitivity of 95.6%, specificity of 91.4%, (NPV) of 88.9%, (PPV) of 96.7%, and diagnostic efficacy of 94.4% and CT sensitivity of 62.6%, specificity of 48.6, (NPV) of 33.3% (PPV) of 76.0%, and diagnostic efficacy of 58%. Conclusion: PET/CT is a better method to evaluate post-therapeutic colorectal cancer patients.