Method in situ hybridization was used to localize 5S rRNA genes on human chromosomes. It was shown that 5S genes are situated on the 1-st chromosome, positions q42.11-42.13 and q 43. The genome organization of 5S rRNA gene cluster was tested by blot-hybridization of fibroblast DNA restriction fragments separated by electrophoresis. It was shown that cluster comprises of repeats with different length and restriction site specificity. The size of HindIII individual repeats-2.6 kb, BamHI-repeats-2.3 and 1.8 kb. The most part of 5S repeats were organized in oligomers. Long 5S rDNA fragments (100 kb) in which BamHI, HindIII, and AccI restriction sites are absent were demonstrated. The results obtained allow to suggest the multicluster organization of human 5S rRNA genes, these clusters are localized in a short distance from each other on the long arm of 1-st chromosome.