Toxicogenomics aims to establish a new method for toxicological evaluation by applying human genome information and newly developed genomic analysis methods to elucidate the genetic interactions between environmental chemicals, drugs, and biological systems. In Japan, the Ministry of Health, Labour and Welfare initiated the "Pioneering Advanced Medical Technology Promotion (Toxicogenomics Field) Research Program" in 2002. This program, led by Professor Tatsuo Nagata, involves collaboration between the National Institute of Pharmaceutical and Medical Devices (NIPND) and 17 pharmaceutical companies. The goal is to develop a more reliable toxicological evaluation method based on gene expression data obtained from DNA chips. The database is expected to be published three years after the program's completion in 2006, serving both early-stage drug safety prediction and the elucidation of harmful reaction mechanisms. Additionally, since 2001, the Ministry of Economy, Trade and Industry and the New Energy and Industrial Technology Development Organization (NEDO) have been conducting the "Comprehensive Evaluation and Management Program for Chemical Substances." One of its projects, "Development of a High-Precision and Simplified Hazard Evaluation System" led by Professor Tomohisa Shirai, focuses on analyzing gene expression changes in liver cells using cDNA microarrays after four weeks of exposure to carcinogenic and non-carcinogenic substances in rats. This research has achieved a 96% accuracy in predicting carcinogenicity. While government-led toxicogenomics research is gaining attention, pharmaceutical companies are also independently exploring this field for early-stage compound screening and the elucidation of toxicological mechanisms. To further advance toxicogenomics, research using human tissues is essential. The "Pioneering Advanced Medical Technology Promotion (Toxicogenomics Field) Research Program" has laid the groundwork for such studies using Japanese human tissues. Additionally, it has been found that individual differences in gene expression are approximately 0.01%. Overall, despite being a relatively new field, toxicogenomics is expected to contribute significantly to the development of more reliable safety evaluation methods for drugs and chemicals in the near future.Toxicogenomics aims to establish a new method for toxicological evaluation by applying human genome information and newly developed genomic analysis methods to elucidate the genetic interactions between environmental chemicals, drugs, and biological systems. In Japan, the Ministry of Health, Labour and Welfare initiated the "Pioneering Advanced Medical Technology Promotion (Toxicogenomics Field) Research Program" in 2002. This program, led by Professor Tatsuo Nagata, involves collaboration between the National Institute of Pharmaceutical and Medical Devices (NIPND) and 17 pharmaceutical companies. The goal is to develop a more reliable toxicological evaluation method based on gene expression data obtained from DNA chips. The database is expected to be published three years after the program's completion in 2006, serving both early-stage drug safety prediction and the elucidation of harmful reaction mechanisms. Additionally, since 2001, the Ministry of Economy, Trade and Industry and the New Energy and Industrial Technology Development Organization (NEDO) have been conducting the "Comprehensive Evaluation and Management Program for Chemical Substances." One of its projects, "Development of a High-Precision and Simplified Hazard Evaluation System" led by Professor Tomohisa Shirai, focuses on analyzing gene expression changes in liver cells using cDNA microarrays after four weeks of exposure to carcinogenic and non-carcinogenic substances in rats. This research has achieved a 96% accuracy in predicting carcinogenicity. While government-led toxicogenomics research is gaining attention, pharmaceutical companies are also independently exploring this field for early-stage compound screening and the elucidation of toxicological mechanisms. To further advance toxicogenomics, research using human tissues is essential. The "Pioneering Advanced Medical Technology Promotion (Toxicogenomics Field) Research Program" has laid the groundwork for such studies using Japanese human tissues. Additionally, it has been found that individual differences in gene expression are approximately 0.01%. Overall, despite being a relatively new field, toxicogenomics is expected to contribute significantly to the development of more reliable safety evaluation methods for drugs and chemicals in the near future.