Prion diseases are a group of etiologically heterogenous diseases. In addition to familial cases linked to mutations of PRNP open reading frame they include also cases of unknown etiology. One of the susceptibility factors to sporadic as well as iatrogenic prion diseases are PRNP polymorphisms. In the present study, we analyzed sequences of the PRNP gene codon 219 of 16 Polish CJD cases and we found heterozygous GAG to GAT changes on the sense strand and only wild type sequence on an antisense strand. The RFLP technique was used to verify this divergence and only wild type sequences were revealed.