Chromosomal abnormalities of the region 12q13-q15 are very frequent among human benign tumors mainly of mesenchymal origin such as uterine leiomyomas, pleomorphic adenomas, lipomas, or pulmonary chondroid hamartomas. Because of these cytogenetic aberrations the HMGI-C gene (HGMW-approved symbol HMGIC) becomes rearranged, with most of the breakpoints located in the large intron 3. In two pulmonary chondroid hamartomas from different patients and one uterine leiomyoma with apparently normal karyotypes, we found identical RTVL-H 3' LTRs fused as ectopic sequences to exon 3 of HMGI-C. Screening of genomic cosmid and plasmid clones derived from intron 3 of the HMGI-C gene for the presence of these RTVL-H sequences showed a cluster of these retrotransposon-like sequences in this region of HMGI-C. Comparing the RTVL-H sequence found in these tumors to known sequences from the literature revealed high homology to known RTVL-H elements.