The structure of type II collagen gene is extremely well conserved but contains a cluster of high frequency polymorphisms in a 2.2 kb area. Here we report the nucleotide sequence of this DNA area, essential for the PCR-facilitated RFLP-analyses of this gene. In the structural analyses we found four differences in the deduced human amino acid sequence when compared to the published bovine amino acid sequence. The donor and acceptor signals and branch point signals required for the splicing events were in agreement with mammalian consensus sequences. The frequency of inverted repeats which could provoke the DNA strand to loop formation and consequently to deletion mutations did not differ from that found in other sequenced genes coding for fibrillar collagens. mutations did not differ from that found in other sequenced genes coding for fibrillar collagens.