Differential diagnosis between diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) becomes a challenge when adequate biopsy is unavailable. The present study aimed to investigate the applicability of DNA cell cycle analysis by flow cytometry (FC) for differentiating between CD10+ DLBCL and FL. Data were collected from 57 specimens where CD5- /CD10+ /light chain restricted B cells were detected. DNA staining was performed using the Coulter DNA Prep Kit. Cell cycle fractions were evaluated by automatic analysis using the ModFit LT software. Histopathological analysis confirmed the diagnosis of CD10+ FL in 30 specimens (52.6%), CD10+ DLBCL in 24 specimens (42.1%), and CD10+ Burkitt lymphoma in 3 specimens (5.3%). A significantly higher rate of DNA aneuploidy was detected among CD10+ DLBCL than FL specimens (50 vs. 13.3% respectively, p = .003). Likewise, DNA index was significantly higher in CD10+ DLBCL relative to FL (1.26 ± 0.35 vs. 1.04 ± 0.16 respectively, p = .004). Notably, the proportion of cells in the S-phase and proliferative fraction was significantly higher in CD10+ DLBCL than in CD10+ FL (S-phase: 15.97 ± 13.94 vs. 4.43 ± 4.41 mean ± SD, respectively, p < .0001; proliferative fraction: 18.87 ± 15.17 vs. 5.78 ± 7.04 mean ± SD, respectively, p = .0001). Using a receiver operating characteristic analysis, optimal cutoffs for S-phase ≥7% and proliferative fraction ≥9% were determined. These values could be used to differentiate between CD10+ DLBCL and CD10+ FL. Including DNA cell cycle analysis in the FC lymphoma assessment panel may be of diagnostic value in differentiating between CD10+ DLBCL and FL when adequate biopsy is unavailable. © 2019 International Clinical Cytometry Society.