We observed 1,163 patient handoffs during 130 ED shift rounds. Of 117 patients with episodes of hypotension and 156 patients with hypoxia, 66 (42%) and 116 (74%) were not communicated at rounds, respectively. One hundred sixty-six handoffs (14%) included a vital sign communication error of omission. In multivariate analysis, no handoff or rounds characteristic, including the ED occupancy rate, was associated with omission errors of vital sign communication