To further determine their role and clinical significance in breast cancer and to explore the relationship between KLK5 and KLK7, the mRNA levels of KLK5 and KLK7 in normal breast tissues, benign breast tissues, primary tumors, and lymph node metastases were detected using a real-time reverse transcription polymerase chain reaction and microarray. The gene discussed is KLK5; the disease is breast cancer.