Diaphragmatic paralysis, a difficult diagnosis in the pediatric age group, has classically been made by fluoroscopy or B-mode ultrasound. We report our experience with TM-mode exploration. Twenty-seven patients suspected to have diaphragmatic paralysis were examined by means of inspiratory and expiratory chest radiography, fluoroscopy and B-mode ultrasound. The diaphragmatic echo was recorded on TM-tracing during spontaneous breathing using coronal oblique scans. Direction, excursion and the pattern of the transition between inspiration and expiration were analysed. In 7 patients examination was normal and TM mode demonstrated movement of normal direction and excursion with a sharp aspect of the transition zone. Diaphragmatic paralysis was present in 11 patients: unilateral in 9 and bilateral in 2 cases. TM mode demonstrated paradoxical movement, reduced excursion and a smooth transition zone. In 9 patients with diaphragmatic dysfunction TM mode demonstrated movement in the normal direction but with reduced excursion and a smooth transition zone. Compared to other imaging modalities, TM-mode records diaphragmatic movements more objectively. It can identify direction of the movement even if they are fast and of weak amplitude and in the case of bilateral paralysis. TM can differentiate paralysis from dysfunction. Moreover, this low-cost, non-irradiating made of imaging can be performed at the bedside and is available on all basic devices.