Post-therapy surveillance imaging in patients with lymphoma remains controversial. We report our experience with positron emission tomography/computed tomography (PET/CT) surveillance in patients with aggressive non-Hodgkin lymphoma in first complete remission (CR). The 138 PET/CTs performed in 52 patients revealed four unsuspected relapses. In one patient, relapse was visualized by fluorodeoxyglucose (FDG) accumulation without any significant CT pathology. The specificity and sensitivity of surveillance PET/CT were 89% and 100%, respectively. The predictive values of positive and negative PET/CTs were 21% and 100%, respectively. The cost of half-yearly routine PET/CT surveillance during the first 2 years in CR was $US8552 per patient and accounted for 81% of the total follow-up costs. PET/CT was effective in detecting unexpected relapse and normal PET/CT supported continuous CR. However, the impact of PET/CT was limited by the high number of false-positive results and PET/CT surveillance was costly compared to CT surveillance.