SIRT6, as one of these seven sirtuins, has been shown to have the therapeutic potentials for treating several human diseases. A fluorogenic assay for SIRT6 has been developed to screen their small molecule modulators based on the recent discovery that SIRT6 is a defatty-acylase (removing long chain fatty acyl groups). However, this assay uses a fluorogenic peptide containing 7-amino-4-methylcoumarin (AMC), which becomes the cause of false positive hits from screenings. To overcome this, we have developed an alternative method called a FRET-based assay suitable for screening SIRT6 modulators, which will be reliable and useful in a high-throughput format since no AMC group present in this assay.