Salvage of young patients with follicular lymphoma (FL) after R-CHOP includes salvage immunochemotherapy followed by autologous stem cell transplantation (ASCT). Previous studies dealing with relapsed Hodgkin lymphoma have shown the prognostic value of PET/CT prior to ASCT. We retrospectively analysed 59 patients with refractory/relapsed FL after first-line R-CHOP who were chemosensitive (as evaluated by CT) to the salvage treatment and who proceeded to ASCT. The role of PET/CT in this setting to define chemosensitivity is not definitely established. So we focused on the prognostic value of PET/CT performed after salvage treatment, before ASCT. The estimated 3-year progression-free survival (PFS) and overall survival were 63.1% (50.9-78.3%) and 90.5% (82.8 - 98.8%), respectively, and did not differ significantly according to their Follicular Lymphoma International Prognostic Index at relapse, conditioning regimen, or type of salvage. PFS was significantly lower in PET/CT-positive patients, according to the International Harmonization Project revised response criteria, with a 3-year PFS of 45.5% (26.6 - 77.8%) versus 72.6% (58.5 - 90.0%; p = 0.039). To better refine prognosis, we applied two types of throsholds: a Deauville five-point scale positive threshold of ≥3 (3-year PFS of 74.9%, range 61.0 - 92.1% %, versus 42.8%, range 24.7 - 74.4%; p = 0.02), and a ≥70% ∆SUVmax threshold between presalvage and pre-ASCT PET/CT (3-year PFS of 72.4%, range 57.5 - 91.3% versus 13.3%, 2.2 - 81.7%; p