Objective To explore the deletion rate,clinical correlation and prognostic significance of lp21 deletion,a novel genetic prognostic index,in patients with multiple myeloma (MM).Methods The interphase fluorescence in situ hybridization (I-FISH) was performed on purified CD 138+ plasma cells from 78 newly diagnosed patients from Sep 2007 to Sep 2012 receiving thalidomide-based chemotherapy by using BAC probe covered lp21.2 region that contains the human cell division cycle 14A (HCDC14A)gene.Deletion rate,the cell percentage of deletion,clinical relevance and prognostic significance were analyzed in myeloma patients.Results Among 78 patients,there were 51 males and 27 females,the median age was 59 (42-81).The deletion rate of lp21.2 was 23.1％.Some patients had amplification (amp) of lp with amp rate of 5.1％ in lp21.2,the amp rate was significantly lower than the deletion rate (P=0.001).lp21.2 deletion was positively correlated with renal lesion (Cr≥177 μ.mol/L),high percentage of plasma cells in bone marrow,high LDH (≥220 U/L) and high β2-MG (P=0.014,0.000,0.010 and 0.022,respectively).With a median follow-up time of 15.0 (1.0-53.5) months,the estimated median progression-free survival (PFS) and overall survival (OS) time for patients with lp21 deletion was (12.0±2.7) and (14.0±3.4) months,however those were (30.0±8.0) and (38.5± 1.8) months in patients without lp21 deletion,respectively (P=0.000).On multivariate analysis,which included complex karyotype,LDH≥220 U/L,renal lesion and del (17pl3),lp21 deletion remained as an independent risk factor for PFS (HR:3.312,95％ CI:1.095-10.017,P=0.034) and OS (HR:4.961,95％ CI:1.487-16.552,P=0.009).Conclusion 1p21 deletion is an important genetic prognosis indicator in multiple myeloma patients.