Computed tomography (CT) as a routine follow-up has been a standard practice for patients with non-Hodgkin lymphoma although it is not recommended in most guidelines. We aimed to describe the value of surveillance CT in detection of disease relapse in patients with diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma grade 3 (FL3) and to evaluate whether relapse detected by different methods influenced outcome. In this retrospective review of consecutive 341 patients with DLBCL or FL3 diagnosed between 2003 and 2009 in complete response (CR) or unconfirmed CR, 113 patients experienced relapses. We found that routine surveillance CT detected asymptomatic relapse in 25 patients (22.1 %; group 1), including 22 of 100 patients with DLBCL and three of 13 with FL3. The first presentation of relapse of the other 88 patients (group 2) included patient-reported symptoms (60.2 %), physical examination (13.3 %), or abnormal laboratory data (4.4 %). For 72 patients received chemotherapy after relapse, the overall survival after relapse was not different between groups 1 and 2 (p = 0.569). The results of our study suggested that routine surveillance CT only has a limited role in the early detection of relapse and the relapse detected by surveillance CT or not has no impact on survival after relapse for patients with DLBCL or FL3.