Introduction: Breast cancer is regarded as the most common cancer among women, and about 6.6% of cases are diagnosed among women 40 years old or younger. Inflammatory cells can regulate the tumor microenvironment and are clearly implicated in tumor development by facilitating proliferation, migration, and survival. Several cytokines, including interferon-a, interleukin (IL)-2, IL-6, IL-8, IL-10, and tumor necrosis factor-a, have essential and coordinated functions in breast carcinogenesis. Materials and Methods: This is a prospective study and observational study conducted in the Department of Pathology, Dr. V.R.K. Women’s Medical College Teaching Hospital & Research Centre over a period of 1 year with a sample of 40 patients. Two to five grams of tumour tissue and another sample from the normal peri-tumoural breast tissue were taken from the resected breast immediately after surgery. Specimen were fixed in 10 % buffered formalin, processed and embedded in paraffin. Paraffin section was stained with hematoxylin and eosin staining for histopathology and grading of the tumour. Immunohistochemistry was done for detection of cytokine IL 10 following a standardized protocol described earlier. Results: The mean patient age was 50 years (range 30-70years). Even though either side of the Breast can be affected in Ca. Breast, for the reasons not known there is slight preponderance to left side breast. Most of the gross tumours were of size 4-5 cms (n=17 i.e, 42.5%) followed by 5- 6 cm (n=10 i.e, 25%). Majority of the patients are categorized as grade-II i.e. 47.5% of cases and next is grade-I tumours i.e. 30.0% cases. All grade 3 tumours expressed strong expression of IL-10 indicating that probably IL-10 expression is more in high grade tumours. Conclusion: IL-10 may serve as a useful biomarker with potential prognostic value as there is statistically significant association of high IL-10 mRNA levels and the breast tumour tissue when compared with peri-tumoral tissue. Evidence from various studies suggests that IL-10 within tumour tissue has an important role in initiation and progression of breast carcinoma. This is also supported by high serum IL-10 levels noticed in such patients, although the mechanisms involved in the process are not exactly known.