Although lymphedema of the arm is a well-known complication of breast and axillary surgery, breast lymphedema has received scant attention. We sought to prospectively characterize breast lymphedema's incidence, associated symptoms, clinical course, and impact on quality of life. Subjects were enrolled prospectively from a consecutive sample of patients undergoing non-mastectomy breast procedures (excisional biopsy or wide local excision ± lymph node removal) and followed for signs and symptoms of lymphedema in the operated breast. Symptoms and distress were serially assessed with 11-point linear analog scales. Breast lymphedema was diagnosed independent of symptoms, based on the distribution and degree of edema and erythema. One hundred twenty-four women were followed for a median of 11 months, and breast lymphedema was diagnosed in 38 (31%) women. Breast lymphedema was more frequent after breast surgery with axillary node removal (49%) compared to breast surgery alone (0%), p < 0.0001. Breast lymphedema involved multiple quadrants in most women and was characterized by edema in 100% and erythema in 79%. Patients with breast lymphedema were significantly more likely than women without breast lymphedema to report symptoms of breast heaviness (65% vs 22%, p < 0.0001), redness (62% vs 29%, p = 0.0006), and swelling (59% vs 22%, p < 0.0001), but symptom-associated distress was low overall. Three of 32 breast lymphedema patients with clinical follow-up developed chronic edema. Breast lymphedema occurs in approximately one-half of women who undergo breast surgery with axillary node removal. The condition is characterized by diffuse skin edema and erythema as well as self-reported symptoms with a low level of distress.