Little is known about physiological parameters of free-ranging walruses (Odobenus rosmarus). The heart rate has been measured electronically during anesthesia (e.g., Born and Knutsen 1990a, Lanthier et al. 1999), but to allow interpretation of such results, and for meaningful monitoring of anesthesia, baseline heart and respiratory rates are essential. Furthermore, such data may contribute to estimation of energy consumption (e.g., McPhee et al. 2003). The heart rate in unrestrained walruses has been estimated based on inspection of movement of the thoracic region as part of pre-anaesthetic assessments (Born and Knutsen 1990a, Griffiths et al. 1993), but to the authors’ knowledge no exact data have been published. In this paper we describe a method for recording resting heart rate in unrestrained wild walruses and present data on respiratory rate and electronically recorded heart rate. The experiment was conducted during 12–16 August 2004 on the terrestrial haulout Sandoen in Young Sound in Northeast Greenland (74◦18′N, 20◦15′W). During summer, this haul-out is used by a group of approximately 60 Atlantic walruses, predominantly adult males (Born et al. 1995, Acquarone 2004). The feeding grounds are accessible from the ice break up in July until the formation of new fast-ice in October (Born et al. 1995, Rysgaard et al. 2003). Ten adult males (estimated body weight >1,000 kg) that had been out of the water for at least 1 h, and were resting at the perimeter of the hauled-out group were studied. Photo-identification was employed to avoid repeated measurements of the same individual. During the experiments, air temperature ranged between 3◦C and 12◦C and wind speed was between 3 m/s and 10 m/s. A battery-operated portable electrocardiograph (Cardiovit AT-4 vet, Schiller AG, Baar CH-6341, Switzerland) was equipped with two custom made cords for unipolar recording. These cords were made from 10 m screened cables ending in an insulated