Persistency assessment is becoming more and more critical for global chemical management. It is an important component of PBT assessments required under global REACH-like regulations. Moreover, in some important new chemical registration regulations like China and Japan, toxicity data requirements are driven by the persistent property. Very limited toxicology information needs to be submitted when the substance is judged as non-persistent. In contrast, a large amount of toxicity data is required if the candidate is determined to be persistent. An integrated testing and assessment strategy has been widely employed for persistency assessment in which ready biodegradation and inherent biodegradation constitute the necessary screening information. However, the former involves testing under very conservative conditions and the latter is not suitable for the difficult substances e.g., poorly water soluble compounds. Enhanced biodegradation has been introduced to judge persistency and fill the gap between screening testing and simulation studies which are costly and time consuming. The term "enhanced" is intended to improve the testing conditions and facilitate the degradation process. Inoculum and exposure regime are two key features for the enhanced study. The inoculum source and biomass optimization are recognized as important for initiation of biodegradation. Test duration and volume are the main factors for the testing design. The prolonged period is intended to aid substances undergoing a long lag phase; the enlarged volume can increase biodiversity of test medium and help biodegradation. In addition to these factors, reference substances, endpoints, pre-adaption and co-degradation are also issues that need to be considered. In summary, it is imperative to standardize the enhanced biodegradation test method in which biodegradation can be evaluated under conditions closer to the real environment and its results will be valuable for the assessment of persistency.