Human uniparental gestations such as androgenetic hydatidiform moles provide a model to evaluate the integrity of parent-specific gene expression,-i.e, genomic imprinting,- in the absence of a complementary parental genetic contribution. Several imprinted genes are characterized so far including the insulin-like growth factor-2 gene (IGF2) coding for a fetal growth factor and the Hl9 gene whose normal function is unknown but which is likely to act as an untranslated mRNA for its tumor-suppressing function. IGF2 is expressed exclusively from the paternal allele while Hl9 from the maternal allele. Such an alternate expression is quite interesting because both Hl9 and IGF2 genes are located close to each other on chromosome 11p15.5. An in situ hybridization analysis has shown strong expression of Hl9 and IGF2 alleles in nine hydatidiform moles. Especially, a prominent expression of Hl9 and IGF2 was detected in cytotrophoblast and the cellular localization was almost paralleled in Hl9 and IGF2 transcripts . Hl9 and IGF2 genes could be expressed either biallelically or monoallelically in the moles. However, IGF2 biallelic expression did not affect allele-specificity of Hl9 expression.. These results suggest that both H19 and IGF2 transcripts are expressed in the same cells and that the functional imprinting of H19 and IGF2 genes in hydatidiform moles can be controlled individually and independently of each other.