Abstract: Purpose and Methods：Utilizing a cell transformed model composed of a human bronchial epithelial cell Iine(BEAS-2B)，BEA&2B cell transformed hy eyelophosphamide(BEAS—CP)and thiotepa(BEAS—T)，cytogenetie alteration a~soeiated with neoplastic trans{ormation of human bronchial epithelial cells was observed Restilts：BEAS一2B cells have near diploid karyotype and genotypically stable Three chromo~mal markers present BEAS-CP cell was mainly diploid with a variable proportion of polyploid celN．Chromosome 14 has lost one of two copies of chromosome and chromo~mal mark M4 has formed Those changes might be lhe original alteration induced by alkylating effect of cyclophosphamide and as the primary alteration involved in transformed initiation，promotion and progression BEAS—T cell mainly consists of po lyploid cells．．~ome cells loss of monosomy of chromosome 8 and 21．BEAS-T∞ft agar selected cells(BEAS—ST)were all polyploid cells and characterized by a high frequency of unstable aberrationsffrom 3％ of BEAS—T 25p up to 34％ of BEAS—ST)．Another speci~ alteration for BEAS-ST is two pairs of the largeness tricentric chromosome．Conclusion：These aberralions have a strong re／atioship with cel malignant transformation and the transformed cells might have the tumorgenesis ability in nude mouse．

Key words: chromosome, karyotype, aberration, immortalized hmnan bronchial epithelial cell line(BEAS-2B), eyclophospharnide transformed celt(BEAS-CP), thiotepa transform ed cell(BEAS—T)