Background: Normal breast tissue cells are sensitive to the number of hormones among which estrogen and prolactin have the most dramatic effect on the breast. Malignant breast tissue cells can behave in this respect similar to the normal cells. Prolactin is necessary for maintenance and proliferation of ductal cells. Alteration in either the qualitative or quantitative expression of prolactin or in receptor could contribute to the pathogenesis of breast cancer. Aim and Objectives: The aim of the study was to evaluate serum prolactin level in pre-menopausal and post-menopausal breast cancer patient and to establish the correlation of circulating prolactin levels with parameters of primary tumor size and to evaluate the prolactin as a potential marker in histologically confirmed breast cancer patients. Materials and Methods: The present study was conducted in the department of general surgery and department of biochemistry on 40 female patients of histopathologically confirmed breast cancer referred by the department of general surgery, rajindra hospital patiala which were taken as study group, while 20 healthy females were taken as control group. Results: The comparison of serum prolactin levels of pre-operative versus post-operative 1 month shows P < 0.0001 and t = 5.668 which is extremely significant. The comparison of serum prolactin levels of post-operative 1 month versus post-operative 6 months was found to be non-significant. The comparison of serum prolactin levels of preoperative versus post-operative 6 months showed P < 0.0001 and t value-6.077 which was extremely significant. Conclusion: It is thus concluded that role of prolactin as an etiological factor in the initiation of the breast cancer in human has not been firmly documented. Furthermore, it still remains to be clarified whether hyper prolactinemia is the result or the cause of breast cancer.