The mucopolysaccharidosis are hereditary diseases. The neurological attack constitutes the principal factor of gravity of these affections. We conducted a retrospective study over a period of 12 years (1988-1999) in the pediatric department of Sfax University Hospital. This study allowed us to observe 11 cases of mucopolysaccharidosis confirmed by an enzymatic proportioning, with 3 cases of Hurler disease (IH), 3 cases of the disease of sanfilippo, (two II A and one III B), 3 cases of the disease of Morquio A (type IVA) and 2 cases of the disease of Maroteaux Lamy (type VI). A sex ratio of 1.75. The parents were cousins in 90% of the cases. The age of revelation ranged between 6 months to 4 years. The clinical examination has found a staturo-pondral delay in 81.8% of the cases, a craniofacial dysmorphy in 100%, deformations of the rachis in 63.6% of the cases, a psychomotor regression in 54.5% of the cases, a medullary compression in 18% of the cases, hepatosplenomegaly in 36.4%, and corneal opacities in 45.4% of the cases. The therapeutic treatment was limited to the symptomatic measures with genetic consulting and antenatal diagnosis.