The acquired serum Chromogranin A (CgA) positivity was followed-up during 15 months in 79 prostate cancer patients referred to maximal androgen blockade (Mab.) In all patients normal CgA values were initially measured. This study was also performed on 24 Stage C-D1 prostate cancer patients left without therapy through their own choice and in 20 controls with benign prostatic hypertrophy. In all these subjects serum PSA, %FPSA and CgA concentrations were measured at three-month intervals and bone scans were performed 1-2 times during the overall monitoring period. After nine months of monitoring, no differences in CgA-positivity between two prostate cancer patient groups had been observed. However, during the last six months of monitoring, the acquired CgA-positivity was statistically significant in treated patients when compared to the untreated group (p<<0.001). Bone metastases were found in 38% of CgA-positive prostate cancer patients (regardless of the therapy status) and in only 6% of studied patients with a steady normal serum CgA concentration. According to the data reported herein we advocate the assessment of serum CgA concentrations at 3-month intervals during hormonal manipulation. The reported results may reawaken the idea of intermittent hormone therapy and, in particular, the replacement of Mab after 9 months by Casodex (Flutamide) monotherapy for a 6-month period.