The basic problem of current animal models is the inability to select and rate the relative effectiveness of new drugs of myeloma of man. As a first step in broaching this problem, results of clinical drug trial studies were used for predicting activity of the drugs in the MOPC 104E plasmacytoma model. Comparison of this model with human myeloma and six additional murine plasmacytomas for drug response indicates close correlation between the reported results in man and the expected results in the animal models. The MOPC 104E model was versatile because drug effects could be rapidly measured in vivo in individual animals. The effect of the drug on the rate of growth, the rate of regression, the doubling time, the number of tumor cells killed and the tumor and drug toxicities on the host could be continuously measured. These measurments were used to select active drugs and to rate the relative activity of the different drugs for myeloma.