Owing to the fact that prostate cancer is the second cause of death behind lung cancer, several diagnostic strategies have been introduced in the past years. Among these prostate specific antigen is widely acknowledged to be the simplest and routine clinical parameter the purpose of this study is to reveal the contribution of the prostate specific antigen (PSA) in the diagnosis and tracking of prostate cancer compared to the PSA density (PSAD). 182 unrelated Tunisian men divided in two groups were considered by this study. The first, formed of 116 patients, comprised 91 subjects with a prostate benign hyperplasia (HBP) and 25 patients developing a prostate cancer (CaP). The second included 66 men without symptomatology of prostate pathologies. The serum prostate specific antigen values are measured in all the cases by immunoenzymatic method. However, the clinical characteristics of all subjects of the first group were determined by recourse to Gleason score, digital rectal examination and prostate echography. Nevertheless, those of the second group were given just for 7 subjects with PSA>4 ng/mL by making a biopsy. The present study shows, on the one hand, a clear correlation between PSA level and prostate pathology frequencies in a Tunisian population, on the other, it demonstrates a considerable relationship between the pathologic PSA level and patient age especially in the 7th decade. Besides, it points out to the contribution of additional parameters essentially the PSAD. PSA measurement can be considered as a reliable tool for early detection, staging, and monitoring of prostate cancer in elderly men even in the absence of clinical signs only for remarkable high levels (>20 ng/mL). Conversely, it cannot be in case of moderate levels (4≤PSA≥20 ng/mL) from where, the need of its combination to other complementary parameters specifically the PSAD which is very beneficial for early diagnosis of the prostate cancer. In fact, when compared to the result of pathological analysis of prostate biopsies, sensibility, specificity, diagnostic efficacy, positive and negative predictive values and the like hood ratio of total PSA were respectively, 100%, 71%, 77%, 0.49, 1.0 and 2.5; those of PSA density respectively 100%, 92%, 95%, 0.86, 1.0 and 12.25.