The testicular-hypothalamic-pituitary axis regulates male reproductive system functions. Understanding these regulatory mechanisms is important for assessing the reproductive effects of environmental and pharmaceutical androgenic and antiandrogenic compounds. A mathematical model for the dynamics of androgenic synthesis, transport, metabolism, and regulation of the adult rodent ventral prostate was developed based on a model by Barton and Anderson (1998). The model describes the systemic and local kinetics of testosterone (T), 5-dihydrotestosterone (DHT) and luteinizing hormone (LH), with metabolism of T to DHT by 5-reductase in the liver and prostate. Also included are feedback loops for the positive regulation of T synthesis by LH, and negative regulation of LH by androgens. The model simulates maintenance of the prostate as a function of hormone concentrations and androgen receptor (AR)-mediated signal transduction. The regulatory processes involved in prostate size and function include cell proliferation, apoptosis, fluid production and 5-reductase activity. These processes are controlled through the occupancy of a representative gene by the androgen-AR dimers. The model simulates prostate dynamics for intact, castrated, and intravenous T-injected rats. After calibration, the model accurately captures the castration-induced regression of the prostate compared to experimental data, which show that the prostate regresses to approximately 17 and 5 percent of its intact weight at 14 and 30 days post-castration, respectively. The model also accurately predicts serum T and AR levels following castration in comparison with data. This model provides a framework for quantifying the kinetics and effects of environmental or pharmaceutical exogenous endocrine active compounds on the prostate.