Apraxia impairs hand gesturing, among other cognitive-motor skills. It impedes nonverbal communication, particularly in left-hemispheric stroke, but also in schizophrenia. The integrity of left inferior parietal lobe (IPL-L) is a critical for gestural control. Furthermore, based on the interhemispheric rivalry model, the function of IPL-L is likely inhibited by the homologue area of the right hemisphere, the IPL-R. We therefore conducted several sham controlled pilot studies using an inhibitory protocol of continuous theta burst stimulation (cTBS) with the hypothesis that transient downregulation of IPL-R may improve gesturing by disinhibition of IPL-L. The proof of concept has been confirmed in healthy subjects (n=46). Accordingly, improved scores in gesturing correlated with microstructural measures (fractional anisotropy) of the splenium, pointing to transcallosal facilitation of the IPL-L as the main mechanism. In addition, down-regulation of IPL-R by cTBS improved gestural performance in patients with stroke (n = 19) and schizophrenia (n = 40). In conclusion, the findings may pave the way for repetitive transcranial magnetic stimulation as an add on treatment of apraxia in neuropsychiatric disorders.