This paper deals with production scheduling of multipurpose batch plants in the presence of equipment failure uncertainty. Uncertainty analysis is incorporated at the production scheduling stage to improve the probability of performing the resulting schedule. This probability will depend on forecasts of equipment failure. The effects of equipment failure on the production schedule are minimised by means of reliability indexes for each plant unit. Avoiding the use of equipment with low reliability indexes is balanced against production requirements (demand). Preventive maintenance tasks may be also introduced to compensate for possible delays produced by equipment with low reliability indexes. The system Operates from an on-line data-base management system which is continuously updated with plant status information. The incorporation of these methodologies into the overall planning framework is also shown and illustrated with case studies.