ABSTRACT: The purpose of this research was to document and compare the before and after levels of consciousness of patients with prolonged consciousness disturbance (PCD) who sat for a specified length of time in a specially designed backless chair (Suwarou-Kun). Three patients were selected as participants using the PCD criteria described by Jennet and Plum in 1972. The Kohnan Vegetative Score (henceforth referred to as the Kohnan PCD Scale) and electroencephalography (EEG) measurements, together with direct observation of subtle changes, were used to record each participant's overt behavior and autonomic responses. A single-case observation/intervention time series design was used in this study. Length of exposure to the intervention and mean exposure time per session were as follows: case 1, 65 days and 30 minutes; case 2, 36 days and 11 minutes; and case 3, 43 days and 36 minutes. The Wilcoxon's rank sum test was used to analyze the pair of Kohnan PCD Scale and EEG scores collected before and at the midway point of each intervention session. Because more than two variables were being measured, the data were reanalyzed using repeated-measure analysis of variance. In cases 2 and 3, there were significant differences in the Kohnan PCD Scale and EEG scores during the "sitting without back support position" (SB) intervention period as well as at the midway point of each session (p < .05) compared with the measurements taken before the intervention. In all three cases, there also were subtle changes during the intervention, for example, eye movement, finger or thumb movement, strength of voice, and salivation. Alpha and beta waves were greater after the introduction of the SB intervention and preceded the behavioral response changes. The SB intervention resulted in at least some improvement in the level of consciousness for each participant. It remains an open question, however, whether longer exposure would have brought about further change. The SB intervention is costly in terms of human time and effort, and its beneficial effects beyond those measured in this study will require additional research.