The purpose of this study was to determine the complete response (CR) rate, failure-free survival (FFS), and overall survival (OS) of patients with poor-prognosis intermediate-grade non-Hodgkin's lymphoma (NHL) after treatment with cyclophosphamide, idarubicin, and etoposide given as a continuous intravenous infusion (CIVI) over 96 hours (infusional CIE), including patients with relapsed/refractory disease and patients with no prior therapy but at least two poor-risk features by the age-adjusted International Prognostic Index. Forty-two patients with previously untreated NHL (N = 24) or relapsed/refractory (N = 18) NHL received cyclophosphamide (200 mg/m2/d), idarubicin (2.5-3.0 mg/m2/d) and etoposide (60 mg/m2/d) given by a 96-hour CIVI every 3 weeks for a maximum of 8 cycles. All patients also received granulocyte-colony-stimulating factor. CR occurred in 10 of 24 patients (42%; 95% confidence intervals [CI] 22%, 62%) treated with CIE as first-line therapy, and in 3 of 18 patients (17%; 95% CI 20%, 32%) treated with CIE as second-line or greater therapy. One-year FFS and OS were 42% and 64%, respectively, in patients with no prior therapy, and 17% and 56% in patients with prior therapy. Severe (grade III) or life-threatening (grade IV) toxicity included leukopenia (59%), anemia (61%), thrombocytopenia (31%), and infection (10%). Two patients (4%) died due to treatment related infectious complications. It is unlikely that infusional CIE produces a CR rate more than about 60% in poor-risk patients with intermediate-grade NHL when used as first-line therapy, or more than about 30% in patients receiving the regimen as second-line therapy. Substitution of idarubicin for doxorubicin in this setting, therefore, is not associated with an improved response rate.