A relatively frequent and often perplexing problem in clinical medicine is the determination of the presence or absence of pulmonary congestion in the patient with suspected heart disease. Equally confusing at times is the differentiation of the symptoms due to pulmonary congestion from those due to primary pulmonary disease, particularly in the elderly patient complaining of shortness of breath. At present, the clinically available laboratory aids to the solution of these problems are radiographic examination of the chest and the measurement of the circulation time and vital capacity. However, the many variables inherent in these tests limit their usefulness, and not infrequently they offer no diagnostic aid in the detection of lesser degrees of pulmonary congestion. In the course of a physiological study of the Valsalva maneuver, we found that this maneuver could be adapted as a simple and reliable bedside method for the detection of the presence or absence