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Background: Diffuse large B‐cell lymphoma (DLBCL) is the most common form of lymphoma. European guidelines recommend FDG‐PET/CT for staging and end of treatment (EOT) response assessment, mid‐treatment response assessment is optional. We compared the Lugano classification and PET Response Criteria In Solid Tumours (PERCIST) for FDG‐PET/CT response assessment in DLBCL head‐to‐head. Methods: We retrospectively included patients with DLBCL who underwent first‐line R‐CHOP(‐like) therapy (2013−2020). Interim and EOT FDG‐PET/CT response were reevaluated using the Lugano classification and PERCIST. Response was dichotomized into complete metabolic response (CMR) versus non‐CMR (interim and EOT) and responders versus nonresponders (interim only). The cutoff for nonresponse at interim was a Deauville score of 5 (DS5) with the Lugano classification and a partial metabolic response with ≤66% reduction in SULpeak using PERCIST (PERCIST66). Results: In multivariable Cox regression (N = 170), DS5 at interim, PERCIST66 at interim, non‐CMR at EOT with the Lugano classification and non‐CMR at EOT with PERCIST were predictive of progression‐free survival (PFS). The Lugano classification and PERCIST agreed perfectly at interim and EOT and with 98.4% for the identification of nonresponders at interim. The accuracy for predicting events within 2 years of diagnosis was 84.2% for DS‐5 at interim, 87.6% for PERCIST66 at interim, 86% for non‐CMR with the Lugano classification at EOT and 83.3% for non‐CMR with PERCIST at EOT. Conclusion: The Lugano classification and PERCIST were equally predictive of PFS. Nonresponse at interim and non‐CMR at EOT were predictive of poor PFS with comparable accuracy for predicting events within 2 years. [ABSTRACT FROM AUTHOR]