Background & Aims: Aflatoxin M1 is one of the most important toxins present in milk and the product of aflatoxin B1 metabolism in liver microsomes. The aim of this project was to study the aflatoxin M1 adsorption ability of polystyrene-hydroxyapatite nanocomposite. Methods: First, the probability of aflatoxin M1 adsorption by the nanocomposite was evaluated using the HyperChem simulation software. Then, polystyrene-hydroxyapatite nanocomposite was synthesized and its properties were determined through chemical deposition. Subsequently, serial concentrations of the nanocomposite were prepared and separately incubated with aflatoxin M1 solution at different temperatures and pH. Finally, the adsorption quantity was measured through high performance liquid chromatography (HPLC). Results: The computer simulation showed that aflatoxin M1 was adsorbed by the nanocomposite. In addition, scanning electron microscope (SEM) images showed that polystyrene and hydroxyapatite nanoparticles were formed and formed a nanocomposite. Image analysis showed that the nanoparticle size distribution was between 50-500 nm. This study revealed that although the adsorption quantity was not affected by temperature, it was affected by pH in all concentrations. The adsorption quantity in a pH of 5 was higher than that in pH of 7 and 9. Conclusion: In the present study, it was shown for the first time that polystyrene-hydroxyapatite nanocomposite can adsorb aflatoxin M1. This study also demonstrated that although the adsorption was not affected by temperature, pH remarkably affected it.