Evaluation of diaphragm function is challenging because no single test has a high diagnostic yield. We describe ultrasound findings in three cases with acquired unilateral diaphragmatic elevation. These cases confirm that sonographic evaluation is a valid tool for identifying diaphragm dysfunction. In addition, ultrasound measurements of diaphragm thickness and the contractility can be used to determine if a diaphragm is paralyzed and suggest the duration of paralysis (i.e., acute or chronic).