Estonian and Baltic Thermal Power Plants are the world largest thermal power plants burning low-grade local oil shale. During the European Dioxin Project the concentrations of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and polychlorinated biphenyls were measured at Baltic Thermal Power Plant in oil shale and fly ash from electrostatic precipitators. The study of PCB and dioxin was carried out by Landesum-weltamt Nordrhein-Westfahlen, Germany. It was concluded that the power plants are probably not major sources of dioxins. It should be noted that the European Dioxin Inventory did not include any measurements of air emission from sources in Estonia.