The androgen receptor (AR) plays a key role in prostate cancer (PCa). Two isoforms of AR, are AR-A and -B, which differ by a lack of the first 187 amino acids in the NH2-terminal transactivation domain of AR-A. Since little is known about the expression and basic function of the AR-A/B isoforms in prostate cancer, the aim of this study was to analyze this possible association. The AR-A, -B and AR-A/B ratio was determined in the tissues of healthy controls, benign prostate hyperplasia (BPH) and PCa by means of Western blot analysis and immunofluorescence. The elevation of AR-A, and -B, as well as the AR-A/B ratio with regard to Gleason scores, were assessed in prostate cancer compared to BPH and normal prostate. In order to further investigate the role of AR A/B isoform function, we transfected PC3 cells with an AR or AR-A expression vector. The overexpression of AR-A and -B significantly decreased the invasion and proliferation of PC3 cells. However, the overexpression of AR-A further decreased proliferation but accelerated the invasion of PC3 cells compared to AR-B. In conclusion, the elevation of AR-A and -B, and the AR-A/B ratio, is associated with prostate cancer occurrence and progression. Furthermore, AR-A could provide a new potential therapy with regard to the decrease in the invasion and proliferation of prostate cancer cells. Our study provides insight into further understanding the biological role of AR-A in its interaction with AR-B and its impact on PCa clinical treatment.