Loss of imprinting (LOI) of the igf2 and h19 genes has been found not only in embryonal tumors but also in common adult cancers. To determine any possible role of genomic imprinting in the development of renal-cell carcinomas (RCCs), we examined the imprinting status of igf2 and h19 in a series of 22 such tumors, and studied its relation to their mRNA expression. Of 14 RCC specimens heterozygous for the ApaI polypmorphism, 7 (50%) showed LOI of igf2. In contrast, for h19 all 9 informative cases maintained imprinting. Furthermore, all 7 cases with LOI transcribed igf2 mRNA at elevated levels, while H19 expression was low regardless of the imprinting status compared with that of background level in each case. These results suggest that LOI of igf2, but not of h19, plays a role in the case of human RCC. However, in contrast to that in Wilms' tumor, LOI in RCC was not associated with any specific down-regulation of h19.