Infections due to triazole resistant Aspergillus fumigatus are increasingly reported worldwide and are associated with treatment failure and mortality. The principal class of azole resistant isolates is characterized by the presence of tandem repeats of 34 bp or 46 bp within the promoter region of the cyp51A gene. Loop-mediated isothermal amplification (LAMP) is a widely used nucleic acid amplification system which is fast and specific. Here 2 we describe a LAMP assay method to detect the 46 bp tandem repeat insertion in the cyp51A gene promoter region based on novel LAMP primer sets. It also differentiated strains with TR46 tandem repeats from those with TR34 tandem repeats. These results showed this TR46-LAMP method is specific, rapid, and also provides crucial insights to enable development of novel antifungal therapeutic strategies against severe fungal infections due to A. fumigatus with TR46 tandem repeats.