Abstract: The analysis of chromosomal Karytype and icstability in 11 patients with MM was repored、of these 3 cases had abnormal chromosomal Karytypes, They had 14q+, 7q+, 17p—and other chromosomal numerical changeh、2 Cases failed to have any mitosis for analysis, The chromosomal instability of the 9 cases with MM is greater than that of the control, The clinical significance of cytogenetic studies in MM was discussed, We suggested that analysis of chromosoma instability is more useful than karytype for evaluating the prognosis in patients with MM.