To determine the prevalence of and contributing factors for chronic arm morbidity including lymphedema in breast cancer patients after treatment and to assess the impact of arm morbidity on quality of life (QOL). A four-question screening questionnaire was developed and mailed to a random sample of 744 breast cancer patients treated curatively in two cancer centers from 1993 to 1997. Patients were without recurrence and at least 2 years from diagnosis. Respondents were classified as with or without arm-related symptoms on the basis of the survey. Stratified random samples from each group were then invited for a detailed assessment of their symptoms and signs, including the presence of lymphedema. Their QOL was assessed by the European Organization for Research and Treatment of Cancer QOL Questionnaire C-30 and by a detailed arm problem questionnaire that assessed various aspects of daily arm functioning. Approximately half of all screened patients were symptomatic and 12.5% of all assessed patients had lymphedema. Axillary dissection (AD) and axillary radiotherapy (RT) after dissection were statistically significantly related to the occurrence of arm symptoms (odds ratio for AD = 3.3, P <.001; odds ratio for RT = 3.1, P <.001). Symptomatic patients and patients with lymphedema both had impaired QOL compared with asymptomatic patients. Treatment for breast cancer is associated with considerable arm morbidity, which has a negative impact on QOL. Arm morbidity should be carefully monitored in future studies involving local treatment modalities for breast cancer.