Quantitative real-time PCR was performed for C13orf19, a gene located on chromosome 13q and previously described to be down-regulated in prostate carcinoma, on different cancer cell lines, on matched prostate tissues from 61 patients with prostate carcinoma and on matched kidney tissues from 23 patients with renal clear cell carcinoma. All data were normalized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH), porphobilinogen deaminase (PBGD) and hypoxanthine guanine phosphoribosyl transferase (HPRT) mRNA expression. A C13orf19 quantitative PCR (QPCR) showed the mRNA to be down-regulated in matched prostate tissues (P=0.007 and lower, paired Student's t-test). However, an at least 1.5-fold C13orf19 mRNA downregulation was observed in samples from 28 patients (46%) and an at least 1.5-fold upregulation was observed in samples from 17 patients (28%). In contrast, C13orf19 mRNA alterations in expression seemed to be random events in kidney cancers.