Previous studies of follicular lymphoma (FL) patients treated heterogeneously have suggested that decreased numbers of regulatory T cells correlates with improved survival. We studied advanced-stage FL patients from a single institution phase 2 trial. All patients were treated uniformly with multiagent chemotherapy and radiation. Tissue microarrays were constructed using diagnostic biopsies available in 105 patients and stained with CD4, CD8, CD25, and forkhead/winged helix transcription factor 3 (FOXP3) antibodies. Both cell content and cell distribution were evaluated. For all antibodies, there were cases with a predominant intrafollicular or perifollicular localization of cells (follicular pattern) while others displayed a diffuse pattern. The median follow-up of living patients was 17.1 years. The International Prognostic Index score predicted overall survival (OS; P = .004) but not risk of transformation (RT). Cell content did not impact survival, while immunoarchitectural patterns of CD4/CD8 were significant for progression-free survival (PFS; P = .056), CD25 for both PFS and OS (P = .002 and P = .024, respectively), and FOXP3⁺ predicted PFS, OS, and RT (P = .001, P < .001 and p = .002, respectively). A Cox multivariate model showed both International Prognostic Index score and FOXP3⁺ pattern were independent predictors of OS (P = .008 and P < .001, respectively), while only FOXP3⁺ pattern predicted RT (P = .004). We conclude that FOXP3⁺ cell distribution significantly predicts survival and RT in FL.