Women who have been treated for gynecological tumors are by far the most frequently affected population group by secondary lymphedema in Western countries. Breast cancer leads the list, followed by carcinomas of the female reproductive organs. The therapy-associated overall risk for secondary lymphedema after breast cancer has been determined by a meta-analysis to be 21%. The lymphedema risk of a sentinel lymph node biopsy (SNL) is about 5% and is therefore significantly lower than that of a complete axillary lymph node removal with 20–21%. Secondary lymphedema is the most important long-term side effect in carcinomas of the mammary gland and the internal and external genitalia of women. Newly formed superficial lymphangiectasias (frog spawn-like blisters with possible lymphorrhea) on the axillary skin should be recognized as a signal for impaired lymphatic drainage in the armpit.