Cyclophosphamide, interferon-alpha and betamethasone are all effective agents for the treatment of multiple myeloma (MM) with different mechanisms of action. The clinical effect of a combination of cyclophosphamide 725 mg/m(2) i.v. days 1 and 3, interferon-alpha 7 x 10(6) IE/m(2) s.c./day, days 1-4 and betamethasone 30 mg orally days 1-4 (CIB) was studied in patients aged 60-75 years with previously untreated MM stages II and III. Granulocyte-macrophage colony-stimulating factor (GM-CSF) 5 microg/kg/day s.c. was administered to all patients from day 5 until the day the granulocyte count exceeded 1.0 x 10(9)/l. CIB was repeated every fourth week. Interferon-alpha 3 x 10(6) IE s.c. t.i.w. was given as maintenance therapy in responding patients.A total of 28 patients (median age: 67 years) entered the study. In all, 12 patients had stage II and 16 had stage III MM. A total of 22 patients (79%) showed an objective response, including five complete remissions (CR) and 17 partial remissions (PR). All seven patients with Bence-Jones MM responded (five CR and two PR). The median response duration time was 14 months (range 5-38+). CIB was relatively well tolerated although febrile neutropenia or septicaemia occurred in 5% of the cycles and a dose-reduction of cyclophosphamide due to grade IV neutropenia was performed in 11% of the patients.CIB seems to be an effective regimen for remission induction in MM patients aged up to 75 years as an alternative to VAD (vincristine, doxorubicin, dexamethasone) if a regimen with intensity higher than that of oral melphalan/prednisone is warranted.