This chapter describes hair analysis in Asian countries, particularly Korea, Japan, and China. Primarily, hair analytical methods of methamphetamine, cannabis, new psychoactive substances (ketamine and synthetic cannabinoids), and propofol were focused on. Recently developed analytical technologies in hair analysis such as metabolomics, imaging analysis, and single hair analysis were introduced and implemented. Asian countries have been using their own analytical methods by referring to international guidelines. These countries are also continuously developing new analytical methods, such as simultaneous analysis by increasing the data sets of abusers and substances. In order to minimize the risk of error, forensic laboratories must continuously develop standard methods and establish processes to ensure comparability, consistency, and traceability of forensic outcomes. International meetings can provide a collaborative space for all countries to share new information, and Asian countries have to actively participate in expanding and strengthening their knowledge of forensic science.