To observe the expression of vimentin in the lenses of vimentin transgenic mice and investigate the role of vimentin in the formation of cataract.The 12.7 kb chicken vimentin genes were microinjected into the male pronuclei of ICR mice. The injected embryos were transferred to the pseudopregnant recipient females and then generated several transgenic mice. Twenty mice developed cataract by cross-breeding. Expression of vimentin in 4 cataractous lenses and 4 normal lenses were detected by ABC immunohistochemical method. Usig SDS-PAGE and Western blot technique, we seperated and measured vimentin in the normal and two cataract lenses, in which one was part opacity and the other was complete opacity.Besides in the epithelial cells, vimentin was overexpressed in the cells in anterior cortex and equatorial region in the lenses of transgenic mice. By SDS-PAGE and Western blot, 57 KD urea-soluble protein bands were seperated in normal and cataract lenses and were reacted with vimentin antiserum specifically. In normal lens, partly and completely opaque lenses respectively, the values of average grey density of these bands were 15.56, 34.59 and 33.06 and the percentages of vimentin in urea-soluble fraction were 7.26%, 9.05% and 9.17%, according to the sum of the grey level values of each band.Over and ectopic expression of vimentin in the Lenses of transgenic mice inhibits the lens cell differentiation and is linked to cataract formation.