The polymerase chain reaction technique was employed to isolate cDNA encoding S26 human ribosomal protein. Based on the known sequence of rat S26 ribosomal protein we have designed primers and amplified the corresponding sequence of human cDNA from total placenta cDNA. The fragment of S26 cDNA was cloned in a plasmid vector and sequenced by the Sanger method. Extremely high homology (87.7%) between coding regions of S26 mRNAs in rat liver and human placenta was revealed. The only amino acid substitution (Ser-->Val) at position 38 was observed. Results of blot hybridization with partially digested human genomic DNA suggest the presence of more than 6 copies of the S26 gene.