Maintenance therapy begins within 5-8 weeks (within 10 weeks if patients undergo stem cell harvest) of initiation of the third course of induction, as follows: oral dexamethasone for 4 days every 4 weeks; and subcutaneous interferon alfa 3 times per week. Patients who achieved less than a 50% reduction in serum M protein or urinary Bence-Jones protein and who experienced less than grade 3 toxicity during induction receive 3 additional courses of pulse dexamethasone concurrently with entry to maintenance therapy and the initiation of interferon alfa.