Chest and abdominal wall movements were assessed as objective indicators of emesis. Thirty-six vomiting episodes in one intact and four decerebrate cats were monitored either by an inductive plethysmograph or by magnetometers applied to the chest and abdomen. The plethysmographic method was found to be the more suitable of these two monitoring techniques because it produced stable, artifact-free recordings with excellent signal differentiation. The occurrence of emesis was validated by simultaneously recording thoracic central venous pressure. Unlike the intrathoracic pressure measurement, spasmodic movements of chest and abdomen did not differentiate retching from expulsion. However, rhythmic abdominal excursions recorded during vomiting were several times greater than those occurring during any other activity. Surprisingly, these movements indicated an increase in abdominal dimensions during vomiting in contrast to the reduction in size observed during sneezing and coughing. We believe that recording of abdominal movements that accompany vomiting might potentially serve as a noninvasive research tool for the study of emesis in cancer chemotherapy.