Prognostic factors and the results of the cyclophosphamide, doxorubicin, vincristine, prednisolone (CHOP) +/- bleomycin treatment in 93 consecutive evaluable patients with aggressive lymphomas are presented. The overall response rate, excluding 7 patients with primary extranodal lymphoma who were in complete remission after surgery, was 83% with a complete response (CR) rate of 69%. Overall survival (OS) rates of all patients and disease-free survival (DFS) rates of complete responders at 4 years were 52 and 66%, respectively. Almost two thirds of the patients could be given at least 75% of the planned chemotherapy doses. Treatment toxicities were in acceptable limits, only 10% of the patients had grade 3-4 hematological toxicity. Age, performance status (PS), stage, number of extranodal sites (ENS) (< or = 1 vs. > 1), B symptoms, serum LDH levels were evaluated as prognostic factors. Univariate survival analysis yielded stage, ENS and PS as significant prognostic factors for OS (p = 0.0009, p = 0.0028 and p = 0.0155, respectively). Only involvement of more than 1 ENS was strongly associated with low CR (p = 0.0479) and high relapse rates (p = 0.0118), and it was also determined as the only independent prognostic factor for OS in patients younger than 60 (p = 0.0015). A modified age-adjusted prognostic index, including ENS in addition to stage, LDH and PS, was found to be more significant than the original age-adjusted International Prognostic Index (IPI) for both DFS (p = 0.0030) and OS (p < 0.00001). In conclusion, modified age-adjusted index may be a convenient alternative to the original age-adjusted IPI to identify high-risk patients with aggressive lymphomas in Turkey and probably also in other developing countries for experimental intensive regimens.