Twenty-eight previously untreated elderly patients (median age 73 years, range 65-88) with aggressive non-Hodgkin's lymphoma were treated with full-dose CHOP chemotherapy between 1989 and 1992. The median of the average relative dose intensity (ARDI) was calculated for the initial cycles needed to achieve a maximal response or to determine progression of disease (1-6 cycles, median 4), as well as for the whole treatment course. For patients aged 65-74, both ARDIs were 0.89. A comparable group of 36 elderly patients who received reduced doses of CHOP from the start, served as a historical control. There was an increase of 11% and 29% in the ARDIs of the full-dose CHOP as compared with the reduced CHOP, in the initial cycles and for the whole treatment course respectively. Grade III-IV leukopenia was the main toxicity observed in 57% of the patients, and 7 patients were hospitalized for fever and leukopenia. There was no treatment-related death. It is concluded that CHOP chemotherapy without initial dose reduction is feasible in patients aged 65-74 years, resulting in high actual dose intensity with a reasonable degree of toxicity.