Laboratory execution system

A laboratory execution system or LES is a "computer system employed in the laboratory at the analyst work level to aid in step enforcement for laboratory test method execution," according to the 2007 Annual Book of ASTM Standards. The general purpose of the LES is to direct the user to follow specific steps to ensure the rigidity of the test method and and the process' end results, though alternate workflow routes may be applied in specific circumstances. The LES may encompass this functionality and more, including tasks like enforcing standard operating procedures (SOPs), validating calculations and instrument interfaces, and acquiring or importing procedural data from other systems into one common system.

For some, an LES may be considered a sub-branch of an electronic laboratory notebook (ELN) specifically made for laboratories engaging in quality control and quality assurance applications, while others may consider it simply a separate set of functionality which may be found in an ELN or a LIMS. Some in the industry suggest the term "laboratory execution system" is a vendor-led morphing of the "method execution system," which was originally designed "to address the problem of standard operating procedure (SOP) compliance."

In France, the English word "Middleware" is used to define a LES.