For more than 30 years, serum PSA has been considered the most valuable tool in early detection of the disease, but its low specificity for PCa has resulted in the detection and treatment of slow growing PCa’s that will not cause harm in a man’s lifetime and a negative biopsy rate of 70% in men with benign prostate diseases such as benign prostatic hyperplasia (BPH) or prostatitis. Here, KLK3 is linked to benign prostatic hyperplasia.