Moebius syndrome is a rare condition characterised by bilateral facial and abducens nerve paralysis. In the present study, it was investigated the effect of the long term facial muscles hypoactivity on temporomandibular joint movements development.Accordingly with Terzis classification (Terzis, 2003), a wide sample of A type and B type Moebius patients was investigated for mandibular range of movements. Moebius patients were compared with a sample of healthy subjects.Both type A and type B Moebius patients develop a severe articular movement reduction, especially during mouth opening. A highly significant difference was found between Moebius patients and the healthy group. No difference was found between A and B Moebius sub-samples.The authors stress the importance of an early adequate rehabilitation of Moebius patients, in order to avoid the limitation of TMJ movement range.