Objective To understand and illuminate the bionomic characteristics of prostate specific membrane antigen (PSMA) and splicing variant PSMA5, through detecting the DNA levels of them in different tumor cell strains and prostate tissues. Methods The fluorescent quantization reverse transcriptase PCR (FQ-RT-PCR) method built up by our research group was used to detect the PSMA and variant PSMA5 DNA levels in different tumor cell strains and prostate tissues. Results The PSMA and PSMA5 DNA levels in tumor cell strains and pathological prostatic tissues were obviously more than those of the normal prostatic tissues (F=3.40, 11.94, both P＜0.05), and the PSMA5 DNA level was much higher than was the PSMA DNA level in prostatic carcinoma tissues (P＜0.05). Conclusions The different expressions between PSMA and PSMA5 in different tumor cells and prostatic tissues show that PSMA5 is more specific than PSMA as a prostate carcinoma tumor marker.