In neuronal cell lines it has been shown that S100B may form heterodimers with S100A6 and that S100B protein expression is co-localised with S100A6 (Deloulme et al, 2000), we therefore performed immunostaining for S100B in 20 cases of organ confined prostatic adenocarcinoma with adjacent benign epithelium. This evidence concerns the gene S100B and prostate adenocarcinoma.