Introduction: Seroma is the commonest complication of breast cancer surgery, and although its consequences most often cause no more than discomfort and anxiety, more important sequelae include flap necrosis and wound dehiscence. Seroma management can be difficult and frustrating for both the patient and surgeon. Numerous methods to reduce post-mastectomy seroma formation have been tried with no consistent success. Methods: Sixty patients were prepared for modified radical mastectomy. Of those, the study group contains 30 patients and the control group contains 30 patients. Study group had axillary space obliteration while the other had the conventional procedure; total drain outputs were recorded daily for all patients prior to drain removal. The drains were removed when the daily drainage was less than 30 ml. Results: This study contains 60 patients, and the study group contains 30 patients, and the control group contains 30 patients. Age, tumor size, No. of positive lymph nodes were of no significant differences to be more concise on the effect of axillary space obliteration. The mean of day of drain removal in the control group was 13.2 ± 1.0 days (9 -18 days) with a mean of total drain output of (4700 ± 90.3 ml) (3722 -4930) while the mean in the study group of day of drain removal was 7.1 ± 1.3 days (6 -12) with a mean of total drain output of 1530 ± 422 ml (range 600 -2100 ml) p < 0.001. Conclusion: Obliteration of axillary space is a valuable procedure that significantly decreases seroma after mastectomy and axillary dissection.