The correlation between both prostate specific antigen levels (PSA) and prostate specific antigen density (PSAD) and age, prostate volume parameters, body mass index, and the International Prostate Symptom Score (IPSS) were studied in a community-based population. A sample of 502 men aged 55 through 74 years was evaluated, excluding those with a serum PSA above 10 ng/ml, those with biopsy proven prostate cancer, and those who had previously undergone a prostate operation. PSA and PSAD did not correlate with the body mass index. Weak correlations were found between PSA and age (r = 0.25; P < 0.001), PSAD and age (r = 0.17; P < 0.001) and between PSA and the total prostate volume (r = 0.58; P < 0.001). PSA did not correlate independently with age after adjustment for volume (P = 0.22). The finding that PSAD correlates with age (r = 0.17; P < 0.001) is partly explained by the incomplete volume adjustment of PSAD which is proved by the positive correlation between PSAD and prostate volume (r = 0.26; P < 0.001). In the main target age-range for prostate cancer screening there is a poor basis for the use of age-specific reference values or volume adjustment for PSA levels in order to increase the clinical usefulness of this serum marker. Comparison of the results of the present study and studies conducted in others regions shows that there may be significant differences in PSA values per age stratum. Further studies are needed to clarify the reasons for these differences.