Thirty-five subjects on volume-cycled mechanical ventilators were surveyed to identify predominating clinical signs associated with amount of tracheobronchial secretions. Variables measured included changes in vital signs, activity, ventilator pressure, tidal volume, presence of abnormal chest movement, adventitious breath sounds, and cyanosis. Secretions were aseptically obtained through a cuffed tracheal tube. Base-line data were gathered ten minutes after the subject was initially suctioned. Fifty minutes after collecting a base line, clinical signs were remeasured, the subject suctioned, and the amount of secretions measured. Seven signs had no observable association, that is, increased or decreased activity, asymmetrical chest excursion, intercoastal retractions, pharyngeal gurgle, local absence of breath sounds, or cyanosis. A biserial correlation coefficient was calculated between each sign and the amount of secretions. Fisher's exact probability chi square was calculated to determine specificity and sensitivity of each sign with secretions over .5 cc. In both statistical tests a change greater than 5mm. Hg in either systolic or diastolic blood pressure was significant (p less than .10). The presence of 6 or more of 15 clinical signs occurred in 90 percent of the subjects with .5 cc. or more secretions and in only 25 percent of those subjects with no secretions. All subjects with .5 cc. or more secretions had six or more signs and/or changes over 5mm. Hg in both systolic and diastolic blood pressure.