Aim:to study the role of PET- CT SCAN as a single imaging modality in the diagnosis of MUO neck. methodology: retrospective study analysis of 51 cases of clinical unknown primary with cervical metastasis . RESULTS: FDG PET CT tracer uptake was detected in 24/51. true positive in 18 cases out of 24,false positive in 6 cases, false negative in 2 cases with sensitivity of 90%, specificity of 82%,positive predictive value of 75%,negative predictive value of 93% and accuracy of 84.91%. conclusion: FDG PET CT can be used as a sole imaging modality in the diagnosis of MUO neck.it is complimentary to endoscopy.