Published protocols for the volumetric assessment of upper-extremity edema differ regarding patients’ posture. The present study was designed to determine the effect of posture on test–retest reliability and mean volume. Thirty women were tested in both seated and standing postures. For the dominant hand, test–retest reliabilities for the seated posture were identical to those for the standing posture. Test–retest reliability was slightly stronger for the nondominant hand in sitting than for the same hand in standing. Both postures afforded clinically acceptable test–retest reliabilities. The mean volumes in sitting were significantly lower than those in standing (p < .0001), thus suggesting that volumetric measures should be considered discontinuous if the patient’s test posture is altered. Mean volumes of the dominant hand averaged 9.3 ml more than those of the nondominant hand. It is suggested that this discrepancy be considered in the establishment of goals for edema control and in the determination of the need for continued edema treatment.