Uncertainty is a very important concern in production scheduling since it can cause infeasibilities and production disturbances. Thus scheduling under Uncertainty has received a lot of attention in the open literature in recent years from chemical engineering and operations research communities. The purpose of this paper is to review the main methodologies that have been developed to address the problem of uncertainty production scheduling as well as to identify the niain challenges in this area. The uncertainties in process scheduling are first analyzed, and thedifferent mathematical approaches that exist to describe process Uncertainties are classified. Based oil the different descriptions for the uncertainties, alternative scheduling approaches and relevant optimization models are reviewed and discussed. Further research challenges in the field of process scheduling under uncertainty are identified and some new ideas are discussed. (C) 2007 Elsevier Ltd. All rights reserved.