Introduction: A breast seroma can develop after trauma to the breast or following procedures such as breast surgery or radiation therapy. Most often, seromas are reabsorbed by the body over a period of several weeks, but in some cases, they can be very troublesome. Also, nipple discharge is very common in women, but a nipple discharge in a previously operated patient for carcinoma can be very alarming. We report a very rare presentation of chronic postoperative breast seroma with mammary duct fistula formation. Presentation of case: A thirty-eight years old female having a 2.1 cm lump in her right breast, presented to us a month after having an excision biopsy of this lump elsewhere. The histopathology report of that excision biopsy showed invasive ductal carcinoma grade III with involved margins. After being discussed in our multidisciplinary team meeting, she underwent re-excision of margins and sentinel lymph node biopsy. This showed no residual carcinoma and negative sentinel lymph nodes. She underwent adjuvant chemotherapy and radiation therapy. But a few months later she presented with pain and swelling in the scar. On her breast ultrasonography, a simple seroma was shown. She was reassured that given time this post-operative seroma should settle. Almost a year later she re-presented with the persistence of a seroma lump along with serous nipple discharge. This nipple discharge would increase on pressing the seroma site suggesting a communication or fistula had formed between the seroma cavity and mammary duct. After a trial of conservative treatment and failing that she was offered surgery. The seroma cavity was excised and the patients symptoms were relieved. Discussion: Seroma formation is very common after breast lumpectomies, the incidence being 3 to 85%. Not only it increases morbidity but it may lead to reoperation if not resolved. Also if there is nipple discharge, it should be evaluated thoroughly for its cause as it may represent an underlying serious pathology. Conclusion: Seroma can present with nipple discharge if it has a fistula with one of the mammary ducts. This is a rare entity and so far very few cases have been reported.