Abstract: Giardia lamblia was long recognized as the most primitive eukaryote,but this is challenged recently by several analyses.With PCR and sequencing techniques,lamin gene of G.lamblia was investigated in the present paper.The results showed that its genome had a gene coding a peptide sequence with distinct features of lamin.For example，its 3 end region had a sequence coding the unique motif CaaX,which attached to the inner nuclear membrane in lamins;like type B lamin genes,it had a 27 bp conserved region,which coded a conserved 9 aa fragment in α-helix rod domain.Simultaneously,there existed some differences between these features of G.lamblia and of metazoan.Our results suggest that G.lamblia has already possessed typical eukaryotic type B lamin (gene) or at least type B.like lamin (gene),the evolutionary position of G.lamblia may not be as primitive as it was considered before.