In the genus Chrysanthemum, repetitive DNA sequences, the dominant part of a genome, are still to be elucidated. To explore the matter, the present study applied fluorescent in situ hybridization (FISH) to the mitotic metaphase chromosome of Chrysanthemum boreale with C0t DNA as probes. Based on DNA re-assotiation kinetics, three kinds of C0t DNA exhibiting different degrees of repetitive nature were fractionated and used as FISH probes to map the repetitive sequences. Signals from all C0t DNAs were successfully observed but their coverage on the chromosomes was different among C0t-1, C0t-10, and C0t-100. C0t-1 FISH signals resulted to have its intensity on the telomeric region and were also dispersed on both chromosome arms except for some distal regions. In C0t-10, signals were observed in all parts of the chromosome with greater intensity around pericentromeric regions. FISH with C0t-100 DNA was observed in bright signals all over the chromosome. Signals of C0t FISH found in this study covered the regions where ribosomal DNAs and telomeric repeats of C. boreale have been distributed (previous report), thus signifying their repetitive attributes. The present results could enhance the efficiency of studying genomes, chromosomes and repetitive sequences of C. boreale and subsequently hasten the realization of the genetic scheme of Chrysanthemum.