Background: Less than half of breast cancer survivors with lymphedema perform self-care as directed. Effective lymphedema self-care is required to obtain acceptable health outcomes. Self-Regulation Theory suggests that objective self-measurement of physiological conditions is necessary to promote self-regulation/ self-care. Bioelectric Impedance Spectroscopy (BIS) represents a potential self-measurement method for arm lymphedema. The purpose of this pilot study was to examine the impact of arm self-measurement on daily selfcare activities and health outcomes in breast cancer survivors with lymphedema. Methods and Results: A pilot randomized clinical trial compared outcomes between breast cancer survivors with lymphedema who self-monitored for 3 months and breast cancer survivors with lymphedema who did not self-monitor. Data were collected at baseline, months 1, 2, 3, and 4. Eighty-six women with lymphedema were screened: 62 were eligible, 50 were enrolled, 10 withdrew, and 1 had incomplete data, thus N = 39. No between group differences were noted in participant characteristics. The self-monitored group had higher days of garment use ( p = 0.005) that remained stable after self-monitoring stopped. The median number of days of simple manual lymphatic drainage increased in the intervention group ( p = 0.004) with a downward trend after self-monitoring ceased. Conclusions: Objective self-monitoring of arms using BIS is possible. Self-monitoring may positively impact self-care behaviors. Highly symptomatic patients may require coaching or other psychological support to improve their self-care. Studies that combine a cognitive behavioral therapy component along with selfmeasurement should be considered as potential interventions to impact lymphedema self-care. Other applications of self-monitoring warrant investigation.