Prostate carcinoma has been a therapeutic challenge. The Dunning tumor, a rat prostate adenocarcinoma tumor model, has been used to evaluate prostate carcinoma treatment protocols. The Dunning tumor subline, MAT LyLu , as described in this report, has been established and characterized as an in vitro continuous cell culture. The cell culture has been stable for greater than 60 passages. The in vitro characteristics of the MAT LyLu cell culture, such as growth rate, loss of contact inhibition, clonogenicity, morphology and tumorigenicity, are consistent with the malignant characteristics of the Dunning tumor subline. The MAT LyLu cell culture has enzyme activities which can be used to characterize the cell line. The establishment of MAT LyLu as a continuous cell culture should provide a controlled approach to evaluate the etiology and treatment of prostate carcinoma.