In order to evaluate the prognostic factors for progression and survival in patients with a low tumor mass asymptomatic multiple myeloma (MM), we studied 59 patients who had a long term follow-up. Cytogenetic abnormalities (using conventional cytogenetics) were observed in 14 out of 45 analyzable patients (31%). An abnormal karyotype and a bone marrow (BM) plasmacytosis > 15% were found to be adverse prognostic factors for progression in univariate and multivariate analysis.