Introduction: Adult T-cell leukemia/lymphoma (ATLL) is a clinically aggressive and heterogeneous entity; hence it is likely that different variants of ATLL have different prognostic factors. Methods: 95 patients with ATLL seen at our institution between 1987 and 2008 were included. Clinical data were compared, according to ATLL variant, using the Mann-Whitney and the Chi-square tests for continuous and categorical variables, respectively. Kaplan-Meier estimates compared using the log-rank test and Cox proportional-hazard test were used for the univariate and multivariate analysis, respectively. Results: Median age was 61 years with male-to-female ratio of 1.07:1. Patients with acute ATLL were more likely to present with bone marrow, liver and spleen involvement, higher β2-microglobulin and lower albumin levels. Poor performance status, high IPI score, presence of B symptoms, high LDH and low albumin levels were associated with a worse survival in lymphomatous ATLL. High LDH, high β2-microglobulin and high PIT score were associated with worse survival in acute ATLL. In the multivariate analysis, low albumin level and presence of B symptoms were independent factors for worse survival in lymphomatous ATLL, and high β2-microglobulin level was independent factor for worse survival in acute ATLL. Conclusions: Aggressive ATLL variants have a distinct, almost mutually exclusive profile of prognostic factors. © 2010 Elsevier Ltd.