Flow cytometric studies of bone marrow DNA and RNA content were conducted in 71 previously untreated patients with multiple myeloma. There was a progressive increase in response rate with rising plasma cell RNA content. The DNA-derived ploidy level also affected chemotherapy sensitivity: only one of 11 patients with either hypodiploidy or biclonal DNA stemlines responded. DNA-RNA-defined marrow plasmacytosis was the only tumor mass-related variable adversely affecting remission induction. Survival was longer in patients with low tumor burden and favorable DNA features. The availability of objective and quantitative pretreatment variables associated with both initial response and survival should permit a risk-based selection of patients for novel treatment approaches.