Prehospital emergency triage involves prioritising patients and deciding who are in the most urgent need of treatment and medical intervention. Currently used triage methods do not support simple sharing of patient-related information, making it challenging for emergency personnel to monitor the number, location and medical status of patients involved in an incident. We present the design and evaluation of an electronic system that facilitates patient tracking and monitoring of vital parameters from the incident scene to place of treatment. The system comprises a patient electronic triage bracelet, which communicates with software applications for patient monitoring. We tested the system in two situations: real-life, daily operations involving real patients over 1 month and in a 1-day, large-scale, mass casualty exercise. Results are presented, along with lessons learned and suggestions for future research.