This study aims to evaluate the clinical and economic impact of incorporating NAT2 genotype-guided dosing of isoniazid to prevent anti-tuberculosis drug-induced hepatitis in the Thai healthcare system.<h4>Methods</h4>A decision tree and Markov model were developed to assess the costs, clinical outcomes, and quality-adjusted life years (QALYs) of NAT2 genotype-guided isoniazid dosing compared to the standard regimen in newly diagnosed pulmonary tuberculosis patients in Thailand. Here, NAT2 is linked to hepatitis A virus infection.