In a retrospective analysis encompassing a 14 year period (1978-92), 22 patients (age range 19-71, median 30 years) were identified as having mediastinal large-cell lymphoma with sclerosis on the basis of clinical and pathological features. At presentation, 15/22 had 'bulky' disease and 11/22 had evidence of superior vena caval obstruction. Thirteen patients had stage II disease (6,II; 7,IIE), nine presented with stage IV disease. Complete remission (CR) was achieved in only 4/22 patients with the initial adriamycin-containing regimen. 'Good partial remission' (no clinical evidence of disease, minimal abnormalities of uncertain significance on radiological investigation) was achieved in a further seven patients and 'poor partial remission' (a reduction in measurable disease > 50%) in four, giving an overall response rate of 15/22 (68%). One patient died within 48 h of arrival at the hospital; 16 of the 17 remaining patients in whom anything less than CR was achieved subsequently received additional, alternative treatment (one chemotherapy, six mediastinal radiotherapy, nine both treatment modalities) but in only 2/16 did this result in any further degree of response. With a median follow-up of 5 1/2 years, 10/22 patients remain well without progression between 6 months and 14 years (5/6 in whom CR was eventually achieved and 5/11 in whom only partial remission was ever documented). The seven patients in whom the initial treatment demonstrably failed have all died. These results suggest that a proportion of patients with this rare subtype of high-grade B-cell lymphoma may be cured by chemotherapy alone and that the presence of a residual mediastinal mass after treatment does not necessarily imply treatment failure. However, patients in whom the initial chemotherapy fails have a very grave prognosis.