We evaluated the prognostic role of 18FDG-PET performed before ASCT in patients affected by lymphoma who underwent high-dose chemotherapy followed by ASCT as first-line treatment for high-risk disease or as second-line or more for relapsed or refractory disease. We retrospectively analyzed 53 consecutive patients, 14 with Hodgkin Lymphoma (HL) and 39 with non-Hodgkin Lymphoma (NHL), treated between February 1999 and October 2006 at our institution, who had a pre-ASCT FDG-PET (pPET) evaluation. Median age was 45 years (range: 18-69). After a median follow-up of 31 months (range: 8-91), 7 out of 16 pPET+ patients and 10 out of 37 pPET- patients experienced lymphoma relapse. The 5-year OS is 90% and 55% (p = 0.01) in patients with negative and positive pPET, respectively. In conclusion, a positive pPET indicates a poorer outcome after ASCT with respect to a negative pPET; this subset of patients should be considered candidate to more intensive or investigational approaches.