OBJECTIVE: Single strand conformation polymorphism (SSCP) and restriction fragment length polymorphism (RFLP) have been used for the diagnosis of spinal muscular atrophy (SMA), but the two methods were complex. In order to find out a simpler and reliable method, this paper studied the feasibility of allele-specific PCR (AS-PCR) in the gene diagnosis of SMA. METHODS: AS-PCR technique was used to detect the deletion of exon 7 of survival motor neuron (SMN) gene in 40 patients with SMA (15 cases of type I, 17 type II and 8 type III) and in 40 healthy controls. All the patients were confirmed to have deletion of exon 7 of SMN_1 by the RFLP method. RESULTS: AS-PCR showed that all the 40 patients had deletion of exon 7 of SMN_1. This result was consistent with that detected by the RFLP method. CONCLUSIONS: AS-PCR technique is simple and reliable for the gene diagnosis of SMA.