This report reviews the background and the present status of the MA-160 cell line. This cell line was reported to have arisen from tissue cultures of a human, benign prostatic adenoma and consequently was used for investigations on the prostate and on hormone-dependent cells. Recent studies using chromosome analysis by banding techniques, glucose-6-phosphate dehydrogenase (G6PD) electrophoretic mobility and a specific prostatic acid phosphatase test indicate that MA-160 is not of prostatic origin but a HeLa [human cervical carcinoma] cell contaminant, arising as a result of intraspecies cell contamination. Whenever spontaneous transformation is observed in vitro and established cell lines are being used in the laboratory, the cells in question should be thoroughly checked with the currently available chromosomal, biochemical and cytochemical methods in order to establish their origin and to rule out interspecies and intraspecies cell contamination.