Background & Objectives: Seroma, is the most frequent post operative complication after breast cancer surgery/modified radical mastectomy (MRM), developing in approximately 30% of cases. The pathophysiology and mechanism of seroma formation in breast cancer surgery remains controversial and not fully understood, as little attention has been paid in the literature to etiologic factors. To prevent seroma formation, it is important to estimate individual risk of seroma formation. Aim of the study was to establish an association between various risk factors of seroma formation and to know whether the risk factors act independently or by synergism. Methods: Patients with breast cancer undergoing Modified Radical Mastectomy were included in the study. The proportions were compared using Chi-square test of significance and the student „t‟ test was used to determine the statistical difference. The data was analysed using SPSS package. Results: Seven out of 67 patients, accounting for 10.4 percent, developed seroma. The mean age of patients who developed seroma was 62.00+12.87 (40 – 75) years. The mean area of raw surface in seroma group was 0.18+0 (0.18 – 0.19) mm2 and the mean BMI in the seroma group was 31.57+4.58 (27.1 – 37.04), surface area and volume where statistically significant as compared to patients without seroma formation. The mean average of post op day 3 drains are151.43 ml (SD+61.76). Hence, the surface area of dissection, BMI and drain output of post op day 3 were statistically significant in comparison to the non seroma formation group. Other variables studied showed no significance with seroma formation. Conclusion: The factors influencing seroma formation following modified radical mastectomy for carcinoma breast were found to be area of the raw surface created on the anterior chest wall, axilla and lateral chest wall and inner surface of the resulting flaps – larger the surface area, higher the seroma rate, BMI and drain output post 72 hours resulted in higher the seroma rate.