Abstract: Purpose To develop a diagnostic tool, the Breast Edema Questionnaire (BrEQ) and to determine its clinimetric properties. Methods The BrEQ was developed based on information from literature, experts and breast edema patients. Content validity, construct validity, test–retest reliability, internal consistency and cut-off point were investigated in a group of breast cancer patients. Construct validity made up two parts; convergent and known-groups validity. Convergent validity was tested by correlating the BrEQ with skin thickness measured with ultrasound (US). Results In part 1 of the BrEQ, symptoms of breast edema were scored from 0 to 10: pain, heaviness, swelling, tensed skin, redness, pitting sign, enlarged skin pores and hardness. Taking into account the International Classification of Functioning, Disability and Health, several activity limitations and participation restrictions were scored from 0 to 10 in part 2. Clinimetric properties of part 1 were examined in 55 patients. US showed that 35 women had breast edema. Content validity was good. Regarding convergent validity, all breast symptoms correlated moderately with skin thickness. The total symptom score had a strong correlation with skin thickness. Concerning known-groups validity, patients with breast edema had a higher total symptom score. Test–retest reliability ranged between moderate and strong. The internal consistency was good for all items and the total symptom score. We identified that a score cut-off point of ≥ 8.5 discriminates between patients with breast edema and those without. Conclusion Part 1 of the BrEQ-Dutch version is a valid and reliable tool for assessing clinical indicators of breast edema.