Breast seromas are tumor-like collections of serosanguineous fluid in breast tissue that occur following excisional biopsy, lumpectomy, mastectomy, and plastic surgery procedures such as augmentation, prosthesis explantation, breast reduction, and breast reconstruction. Mammographically seromas are water-density masses located at the surgical site. They exhibit features characteristic of fluid collections on sonographic evaluation. This article reviews the spectrum of imaging findings associated with breast seromas.