Introduction: Breast cancer is the most common malignant tumor in women worldwide, including Croatia, where approximately 3,000 women are diagnosed with it each year. Breast cancer treatment involves surgical procedures, chemotherapy, hormone therapy, and immunotherapy. Surgical interventions, including partial or complete breast removal and axillary lymph node dissection, often require drainage to control the drainage of bloody content and lymph from the wound. Drains play a crucial role in postoperative monitoring and facilitate the detection of complications such as bleeding. In most cases, drains are removed within the first 24 to 48 hours after surgery, except in situations where the drainage does not decrease below 50 ml in 24 hours, which can occur during axillary dissection or breast reconstruction. Modern breast surgery also focuses on reducing the radical removal of lymph nodes, which can result in reduced seroma formation in the postoperative period. Objective: The aim of this study is to examine the association between the duration of drainage and the formation of seroma following axillary lymph node dissection in breast cancer patients. The study compares differences in removing the drain within 48 hours versus removal after 48 hours. Methods: The study was conducted at the Department of Oncoplastic and Reconstructive Surgery, Clinic for Tumors, Clinical Hospital Center Sisters of Mercy. It included 100 patients undergoing surgery on axillary lymph nodes. Half of the participants had the drain removed within 48 hours after surgery, while the other half had the drain removed after 48 hours. The amount of seroma after drain removal was monitored at follow-up appointments 5-7 and 14 days after surgery, with necessary punctures and evacuations. The obtained results were descriptively and graphically presented for both groups of patients. To test the hypothesis H, differences in the amount of seroma between the two groups (drain removed after 24-48 hours and after 48 hours) were analyzed, and the relative risk (RR) for prolonged seroma formation was calculated. Results: The results showed a significant difference in the distribution of drain duration according to the type of surgery and axillary procedure. In patients with drain duration longer than 48 hours, there was a significantly higher prevalence of reconstructions and breast-conserving surgeries, and axillary dissection was more frequently performed. Additionally, there is a significant positive correlation between the number of removed lymph nodes and the amount of seroma after 5-7 days and after 14 days, indicating that a larger number of removed lymph nodes results in greater seroma accumulation. Conclusion: This study confirmed a clear association between the duration of drainage application and the formation of seroma after axillary lymph node surgery in breast cancer patients. The initial hypothesis that longer drainage duration results in greater seroma accumulation was confirmed. The importance of careful assessment and planning of postoperative care to reduce the risk of seroma and related complications is emphasized. These results provide a basis for further research and the development of new strategies to prevent seroma formation. Additionally, the study contributes to clinical practice by enhancing understanding for improving postoperative care and seroma management in breast cancer patients.