Abstract. Prostate cancer (PCa) is the most frequently diagnosed non-skin cancer and the second highest cause of cancer-related mortality in adult males worldwide. PCa is highly dependent upon androgen receptor (AR) signaling for cell proliferation and survival. The AR therefore plays a vital role in the develop ment and function of normal and malignant prostate cells or PCa recurrence. The present study aimed to examine the ubiquity of AR amplification in PCa recurrence, even in the absence of androgen. For this purpose, specimens were collected from 37 patients. The amplification of AR and the number of X chromosomes were determined by two-colored fluorescence in situ hybridization analysis. The automated image analysis was used to determine the protein expression of AR. Clinical characteristics and survival in patients whose tumors showed or did not show AR amplification and in X-chromosome polysomy with PCa recurrence has also been compared. The results showed that >35% of patients (13 specimens) exhibited AR amplification. It was also observed that AR was immunostained more intensely in the tumors with amplified AR compared with those tumors with non-amplified AR. This study demonstrated an influential role of AR in tumor growth and progression even after the deprivation of androgen, as well as showing the potential contribution of AR amplification to AR activation even in the relative absence of androgen.