The performance of a new colorimetric CO2-indicator (Colibri) was assessed in mini-pigs. It performed well during 8-hour procedures. Neither nitrous oxide, nor halothane, nor carbon monoxide, nor intratracheal application of drugs (epinephrine, atropine, lidocaine, and naloxone) interfered with its function. It gave a distinct color change at high ventilation frequencies up to 120/min. The only problem observed was difficulty in matching the colors displayed with the comparison color chart provided. The Colibri's performance seems at least equal to that of the EasyCAP detector, although both devices share some disadvantages (no alarms, semiquantitative, difficult reading in the dark). After initial control of endotracheal tube position by an esophageal detector device, both the Colibri and the EasyCAP seem suited for monitoring of ventilation and circulation if quantitative capnometry is unavailable.