Polybrominated diphenyl ethers (PBDE) because of their physical and chemical properties belong to Persistent Organic Pollutants (POPs). They are stable in the environment and due to lipophilic properties, have potential impact to human health. Currently these compounds are present in all kind of environmental samples all over the world. Levels of PBDE in samples originated from U.S. are higher than levels reported from Europe and Japan, what may be linked to common use these flame retardants in this country. Environmental (including humans) concentration of PBDE have increased rapidly in the last decade. Predominant congeners detected in all matrices are BDE-47, -99, -153, -209. Recent Swedish report however noticed decrease of PBDE concentrations what can be consequence of phase-out of these compounds in this country. It has been suggested that the environmental levels of PBDE may influence human nervous and immunological system as well as they may disrupt hormonal homeostasis. Research studies suggest also that the exposure to polybrominated diphenyl ethers may be associated with increased risk of cancers. Therefore, continuation of research concerning occurrence and toxicity of PBDE has reasonable grounds.