A physical map of the 5S and 18S-26S rRNA genes was determined using bi-color fluorescence in situ hybridization technique in A. victorialis var. platyphyllum. 5S rRNA genes were positioned in the intercalary regions of the short arms in homologous chromosomes 6. Two major loci of the 18S-26S rRNA genes were detected in the secondary constrictions flanking with a pair of satellite and terminal region of short arm in chromosome 4. And two additional minor loci were heterotype, representing one signal on the terminal region of the short arm in one homolog of chromsome 2, and other on one homolog of chromosome 6 with linked 5S rRNA loci. In addition chromomycin A3 (CMA3) fluorescent banding method was used to identify the relation between Nucleolus Organizer Region (NOR) sites and CMA3 positive heterochromatin sites. In homologous chromosome 4 showing 18S-26S rDNA hybridization signals revealed also distinct CMA3 positive band.