Karyological analyses and rRNA/DNA hybridization experiments were carried out inBellevalia romanaandB. dubia(Liliaceae).B. romana(2n=8) has four short NORs and 3,200 genes for ribosomal RNA; B. dubia (2n=8) has six NORs clearly longer than those ofB. romanaand 9,800 rRNA genes. The gene numbers are calculated on the basis that both species possess 24 × 10−12g/2C nucleus. A correlation between cytological and molecular hybridization results is made.