This paper will discuss the aspects of bioburden reduction in a manufacturing area or cleanroom during operational shutdown or for routine maintenance scheduling. Relevant regulatory requirements are overviewed, along with the factors constituting aseptic cleaning. What is aseptic cleaning? Asepsis describes a system that is free from disease-causing micro-organisms, something which any pharmaceutical or biotech manufacturer would not want in their final product. During manufacturing periods, conditions are kept as clean as possible, with annual shutdown allowing general cleaning and maintenance to be carried out.