Genetic causes of mental retardation (MR) are heterogeneous, but subtelomeric rearrangements are an important one. MLPA technique provides the best results in case detection. We have used MLPA to identify subtelomeric rearrangements in children with idiopatic MR. The protocol included: clinical selection; karyotype; antiFMRP test; MLPA. We have selected cases using de Vries diagnostic score. Patient data were recorded in a database. The group was formed of 142 MR children. In 24 (16.9%) the karyotype was abnormal. 16 cases (11.3%) presented speech delay/autism, but antiFMRP test was normal. 60 MLPA tests were done: 46 cases (76.7% were normal, 6 (10%) abnormal, 4 (6.7%) had polymorphism and 4 (6.7%) could not be interpreted. Clinical features of the cases identified are illustrated. In conclusion, the diagnostic score is useful in case selection for further testing and MLPA proves to be efficient in diagnosing subtelomeric rearrangements as a possible cause of idiopatic MR.