A novel mouse heart-specific gene, Lrrc10（GenBank Acc No. AF527781）, was cloned from mouse embryo heart by application of EST assembly and RT-PCR. The cDNA of Lrrc10 was 1 410 bp and intronless. This gene was mapped to mouse chromosome 10D2 by BLAST search to mouse genome. The longest ORF of the cDNA encoded a putative proteins of 274 amino acids. Seven leucine rich repeat motifs were present between 53 amino acid to 212 amino acid. No known gene or protein was significantly homologous to Lrrc10 or its deduced protein. However, XM-137268, a predicted human gene submitted by NCBI genome annotation project，shared high identity to Lrrc10. It may be concluded that XM-137268 was the uncloned human orthologue of Lrrc10. BLAST to EST database showed that cDNA of Lrrc10 was supported by 18 ESTs, all of them were from mouse heart. RT-PCR performed on a panel of different mouse tissues demonstrated that expression of Lrrc10 was strongly in heart, low in lung, not or very weakly in other tissues. These results suggest that Lrrc10 is a novel heart specific member of leucine rich repeat superfamily. As far as, no heart-specific member of this family was reported before.