We sought to determine the clinical and immunohistopathological prognostic factors for overall survival (OS) in adult patients with post-transplant lymphoproliferative disorders (PTLDs). Eighty-four patients diagnosed with PTLDs between 1980 and 2004 at the University of Pittsburgh Medical Center were identified. Immunohistochemical staining was performed on tumor tissue at the time of diagnosis for the following proteins: Bcl-2, Bcl-6, c-myc and p53. The median survival for all patients was 20.8 months, 95% CI: (7.4-77.6). On univariate analysis for OS, the following poor prognostic factors were identified: age at transplant >60 years (p = 0.024), multiorgan transplant (p = 0.019), ECOG > 2 (p < 0.0001), grafted organ involvement (p < 0.0001), extranodal disease (p = 0.011), early (<1 year) PTLDs (p < 0.0001), stage IV (p = 0.0017), EBV positive (p = 0.012) and elevated white blood count (p = 0.010). Good prognostic factors included ECOG<2 (p < 0.0001), late (>1 year) PTLDs (p = 0.002), early stage at diagnosis (stages I and II, p = 0.005), nodal disease (p = 0.0053), monomorphic disease (0.0034), initial immunosuppression reduction (p = 0.0015) and use of rituximab (p = 0.045). Bcl-2 but not Bcl-6, c-myc, or p53 correlated with poor survival, p = 0.0036. This study identifies new clinical and pathological markers for poor survival in PTLDs.