Summary Inter-section hybrids were successfully obtained from reciprocal crosses between tetraploid Primula denticulata (section Denticulata) and diploid P. rosea (section Oreophlomis) by applying ovary culture 4 weeks after pollination. Differences in ploidy levels were found in these hybrids by flow cytometric analysis and by counting chromosome numbers. When P. denticulata was used as maternal parent, all the hybrids were triploid, with two genomes of P. denticulata and one genome of P. rosea. In contrast, when P. rosea was used as maternal parent, two genome-type hybrids were obtained: one was a triploid hybrid, with the same genome combinations as those obtained when P. denticulata was used as maternal parent, and the other type was a tetraploid hybrid with two genomes of each species. These results suggest that unreduced (2x) gametes were formed only in the female side of P. rosea.