Objective. A somatotopy inside the human globus pallidus (GP), based on intraoperative microelectrode-recordings during passive or active movement, and on clinical results of deep brain stimulation (DBS) in movement disorders, has been reported. We aimed to report a GP somatotopy, observed in one parkinsonian patient based on dystonic motor side effect assessment during acute stimulation, and related to MRI anatomy. Methods. A 68 year old parkinsonian (female, 16-year history; suffering mainly from limb and trunk dyskinesia) underwent bilateral stereotactic DBS surgery in internal GP (GPi) based on direct MRI targeting. We identified the different GP parts on T2-weighted coronal slices: external GP (GPe) and lateral and medial subdivisions of GPi (GPil, GPim). Controlateral dystonic movements were noted during acute intraoperative stimulation under local anaesthesia (1 or 2 mm step; mean current = 0.97 +/- 0.14 mA) along the distal 10 mm on 3 parallel tracts (2 mm distant; left hemisphere: central, lateral and medial; right hemisphere: central, anterior and lateral). On the 6 tracts (45 GP checkpoints), the involved body parts (face, upper and lower limbs) were matched with the anatomic structures. Postoperatively, chronic DBS dramatically improved dyskinesia (electrodes implanted on the central tracks). Results. GPe, GPil and GPim seemed to be characterized by a segregated body map. We found inside each structure a rostrocaudal organisation: face, superior part; upper limb, intermediate part; lower limb, inferior part. Conclusions. Motor side effect analysis is an interesting tool for somatotopic investigations. The GP somatotopy related to these clinical conditions has to be confirmed.