Summary Detailed karyotypes and the fluorescence in situ hybridization (FISH) using 5S and 18S rDNA probes was applied to 3 species of the genus Juniperus. The number of chromosomes of J. chinensis var. sargentii and J. lutchuensis was 2nϭ22, except for J. chinensis var. procumbens (2nϭ44). Chromosomal sites of 5S rDNA were on one pair of the short arm of the median-centromeric chromosome and 18S rDNA were at the secondary constriction. No minor signals of 5S and 18S rDNA probes were detected in the Juniperus chromosomes. We developed karyotypes using McFISH with 5S and 18S rDNA, and reported the first time chromosome makers of the family Cupressaceae.