Purpose On a regular basis, the intensivist encounters the patient who is difficult to wean from mechanical ventilatory support. The causes for failure to wean from mechanical ventilatory support are often multifactorial and involve a complex interplay between cardiac and pulmonary dysfunction. A potential application of point of care ultrasonography relates to its utility in the process of weaning the patient from mechanical ventilatory support. Methods This article reviews some applications of ultrasonography that may be relevant to the process of weaning from mechanical ventilatory support. Results The authors have divided these applications of ultrasonography into four separate categories: the assessment of cardiac, diaphragmatic, and lung function; and the identification of pleural effusion; which can all be evaluated with ultrasonography during a dynamic process in which the intensivist is uniquely positioned to use ultrasonography at the point of care. Conclusions Ultrasonography may have useful application during the weaning process from mechanical ventilatory support.