Motor imagery is the mental rehearsal of movements, which is not accompanied by overt action. Kinesthetic motor imagery involves a first-person perspective that draws on an internal representation of the action. Motor imagery and the actual performance of movements share some common representations in the brain, which include the lateral premotor cortex and the supplementary motor area. Kinesthetic imagery of movements of different body parts activates different subregions of the premotor cortex, which are organized somatotopically. To investigate the effect of task complexity, we used functional magnetic resonance imaging (fMRI) and transcranial magnetic brain stimulation (TMS) in 12 right-handed volunteers, who imagined simple and complex movements of the dominant and non-dominant hand. Premotor, posterior parietal and cerebellar regions were more active during mental rehearsal of the complex task than of the simple task. Futhermore, corticospinal excitability (TMS) increased in a task-dependent manner. Regardless of task complexity, parts of the left lateral premotor cortex were active during imagery of movements of both the dominant and the non- dominant hand. This effector-independent activation of left premotor areas suggests a left hemispherical dominance for kinesthetic movement representations.