A new method of mismatching PCR-RFL P was performed in our lab in ge- netic diagnosis of spinal muscular atrophy(SMA) and controls.Our data shows:9cases in 1 0 presumed SMA children are positive,i.e. deletion of telomeric SMN gene.One case is negative.2 0 cases of normal familial members and2 0 cases of normal controls are all nega- tive.Our results matches the criteria and reports of foreign countries.The method we used is highly specific,sensitive and useful and is suittable for genetic diagnosis of SMA and its prenatal diagnosis.