Background: Seroma is the most common complication occurring after surgery for breast cancer, leading to patient discomfort, recurrent aspirations with the risk of inflammations, long hospital stay, delayed wound healing, skin flap damage, delay in treatment with adjuvant therapies, and high surgical costs. The purpose of our study is short term follow up" within two months after operation" to compare the effectiveness of using Tetracycline and reducing the dead space in reducing seroma after Modified Radical Mastectomy (MRM). Patients and methods: Interventional study was applied on 56 females having breast cancer to evaluate different techniques for reduction of seroma formation after modified radical mastectomy at department of general surgery, Zagazig University Hospitals, during the time from October 2018 to April 2020. Patients were divided into two groups each one enrolls 28 patients Group A: we used tetracycline, suction drain and tight bandage while in Group B: we used mechanical closure of dead space, suction drain and tight bandage. All patients were subjected to history taking, complete clinical examination, Laboratory tests and breast ultrasound. Results: In this study the percentage of seroma occurred in total cases was (26.8%) this is considered good results when compared to worldwide percentage (73%). In group A (Tetracycline) seroma occurred in 32% of 28 cases and 21.4% of 28 cases in group B. Conclusion: There was no significant difference between using Tetracycline and closing the dead space in decreasing seroma formation after MRM.