Prognosis of DLCL patients is variable and associated with well-deยฎned risk factors. In the past decade several pretreatment variables have been incorporated into prognostic models to predict the death risk of individual patients. The International Prognostic Index (IPI), developed in an international consensus study, has been one of the most widely accepted of these models. In our study we applied some of the major prognostic models proposed for DLCLs in a cohort of 111 patients uniformly treated with a CHOPlike regimen in order to compare their sensitivity and speciยฎcity. We also evaluated the possibility of improving the IPI with the inclusion, from among the variables analysed, of serum b-2 microglobulin level (b-2M). The sensitivity, reยฏecting the ability to predict all failures in the cohort of patients as a whole, has improved from 45 to 73 per cent when the b-2M-IPI model is compared with IPI, without a signiยฎcant loss of speciยฎcity. Based on these results, the b-2M-IPI may be useful for identifying the subset of patients with very poor prognoses. Therefore, the use of the serum b-2M value in addition to the IPI may help in selection of the patients with DLCL at higher risk for treatment failure, and identiยฎcation of those who may require speciยฎcally tailored therapeutic approaches.