BACKGROUND. Benign prostatic hyperplasia (BPH) is mainly a stromal process, showing an increased ratio of stromal to epithelial elements, a collagen type III downregulation, and a collagen types I and IV upregulation. Little is known about elastin gene expression in BPH tissues due to difficulties related to extensive alternative splicing of the elastin gene. Therefore, we analyzed and quantified elastin gene expression in BPH. METHODS. A competitive reverse transcriptase-polymerase chain reaction (competitive RT-PCR) quantitative technique was used, and a quantitative elastin mRNA analysis with normal (n = 10) and BPH (n = 12) tissues was performed with two newly designed elastin primers. Small tissue samples (4-8 mg) were homogenized and sonicated, and cDNA was synthesized from mRNA using a RT reaction. Various target (wild-type) elastin cDNAs with unknown concentrations were competitively coamplified with known serial dilutions of the control mutant template, differing from the target cDNA by a short deletion. Gel fractions and computerized densitometry, were performed and cDNA concentration was calculated by linear regression. RESULTS. The primers identified in our study (BOB-1 and BOB-2) accurately amplified a consistent length of the elastin cDNA, avoiding areas of alternative splicing. The average elastin mRNA concentration in BPH tissues was 53 attomole/mg ยฑ 11.6 vs. 140.6 attomole/mg ยฑ 19.6 in normal prostatic tissue (P = 0.019). The variation within every sample was less than 10%. CONCLUSIONS. Our observations suggest a significant downregulation (70%) of the elastin mRNA gene in the transition zone of BPH patients.