This article reviews the outcome of comprehensive investigations conducted in our laboratory at CMES, Ehime University over the past three decades on the distribution, sources, temporal trends and toxic impacts of the persistent and bioaccumulative organohalogen contaminants in Asia-Pacific region with a particular emphasis on developing countries. Results of multi-media monitoring studies were compiled and discussed to provide in-depth understanding on various issues of dioxins and organohalogen contamination in both ambient environment and animals including humans. Prominent contaminations were found in the regions where they have been heavily used. The eastern Asian region is probably a potential source of pollution, particularly by the new contaminants such as polybrominated diphenyls ethers. These groups of contaminants, together with polychlorinated biphenyls, exhibited either decreasing or increasing trends depending on the extent of industrialization in Asian developing region, indicating the necessity for long term monitoring. The open dumping sites for municipal wastes in major cities are significant sources of many toxic chemicals, and these areas are probably one of the challenges for future research due to the long term impacts on the environmental quality and human health. The formation of dioxins and related compounds in such dumping sites and their elevated residues found in breast milk of residents living in and around warrant long term impacts of dioxins upon next generations. Comprehensive and long term monitoring programs are urgently needed with close collaboration and proper capacity building in Asian developing countries in order to mitigate dioxin and organohalogen emission and their risk on ecosystems and human health.