Background: In critical care, part of the physiotherapist's respiratory assessment aims to identify parenchymal pulmonary pathology, which may be amenable to respiratory physiotherapy. In addition to clinical assessment, the tools that are most readily available to the respiratory physiotherapist to distinguish between acute pulmonary pathologies include auscultation and chest Xray. The limited diagnostic accuracy of these tools may not allow for the accurate differentiation between conditions such as lung collapse, consolidation and pleural effusion. Although computed tomography allows for this differentiation, it requires patient transport and exposes the patient to increased risk and high levels of radiation. Diagnostic lung ultrasound (LUS) has emerged as a highly sensitive bedside diagnostic tool with high level evidence to support its use for the differentiation of various common acute pulmonary pathologies. In this review, the diagnostic performances of auscultation, chest Xray and LUS are reviewed, and the usefulness of LUS as an adjunct to respiratory physiotherapy assessment is discussed. The issues surrounding training physiotherapists and the implementation of LUS are also explored. Methods: The method used is a narrative review of the literature. Conclusion: To our knowledge, LUS is not routinely utilized by critical care physiotherapists. However, its superior sensitivity and specificity would enable the physiotherapist to make an accurate, timely and point of care diagnosis of lung pathology and determine whether the pathology is amenable to respiratory physiotherapy.