There is rising evidence that ventilator-induced diaphragmatic dysfunction (VIDD) is not just an artifactual finding from animal studies, but actually occurs in humans undergoing invasive mechanical ventilation. Initial research findings in humans have demonstrated that periods of controlled invasive mechanical ventilation lasting just 18 - 69 hours can lead to a marked reduction in diaphragmatic myofibers. More recently, it has been shown that even short periods (e. g. two-hours) of controlled invasive mechanical ventilation are sufficient to initiate VIDD. The evidence available at present suggests that VIDD is most likely based on increased proteolysis of the respiratory muscles. Moreover, VIDD seems not to be part of a general muscle wasting process, as suggested by the fact that e. g. the human latissimus dorsi and the pectoralis major muscles seem not to be subjected to early muscle fiber atrophy when directly compared to the human diaphragm. Novel in vivo data have also revealed that VIDD in humans is associated with a reduction in diaphragmatic force generation after only one day of controlled invasive mechanical ventilation. This impairment was observed to progress further over the one-week investigation period. The introduction of a simple bedside ultrasound measurement of diaphragmatic function is of great importance to the clinician, as it may serve as a surrogate measure for VIDD, with high predictive value. Regarding potential therapeutic interventions against VIDD, the primary aim should be to encourage sufficient diaphragmatic use in susceptible patients so as to avoid VIDD; this approach remains in fundamental contrast to that of reducing respiratory muscle load by (invasive) mechanical ventilation.