Abstract： Objective To explore the application of multiplex ligation-dependent probe amplification (MLPA) in the gene diagnosis of X-linked Alport syndrome (XLAS).Methods MLPA was used to detect and confirm large deletion mutations in COL4A5 gene in 3 XLAS patients with deletion mutation from cDNA.Results Patient 1 had a deletion from exons 22 to 24 in COL4A5 gene,patient 2 a deletion of exon 30 in COL4A5 gene and patient 3 a deletion of exons 1 and 2 in COL4A5 gene and exons 1 and 2 in COL4A6 gene.All these mutations were detected by reverse transcription-polymerase chain reaction (RT-PCR) and MLPA coincidently.Conclusion As a new method for gene diagnosis of XLAS,MLPA can be used to detect large deletion mutations in COL4A5 gene.