Objective To investigate the expression and clinical significance of lysophosphatidic acid receptor 5 (LPA5) protein in breast cancer tissues. Methods The specimens of breast cancer tissues and adjacent tissues of 80 breast cancer patients from January 2015 to December 2016 in the First People's Hospital of Yongkang were selected in the study.The expression of LPA5 in breast cancer tissues and adjacent tissues was determined by immunohistochemistry.The clinical case characteristics of patients were collected. Results The positive expression rate of LPA5 in breast cancer tissues(72.5%) was higher than that in adjacent tissues(8.75%)(χ2=67.394, P 0.05). There were no significant differences in the positive expression rates of LPA5 in the breast cancer tissues among luminal type, human epidermal growth factor receptor 2 (Her2) overexpressing type and triple negative type (P>0.05). The disease-free survival rate(86.3%) and overall survival rate(87.5%) of patients with negative expression of LPA5 in breast cancer tissues were higher than those in breast cancer tissues with positive expression (65.0%, 66.3%)(χ2=4.517, 4.328, all P<0.05). Conclusion LPA5 expression is up-regulated in breast cancer tissues, and LPA5 may be involved in the development and progression of breast cancer, which is closely related to the prognosis of breast cancer. Key words: Breast neoplasms; Immunohistochemistry; Receptors, lysophosphatidic acid; Prognosis; Staging; Lymph node metastasis; Survival