One of the major advances in the scheduling of multipurpose plants over the past decade has been the increasing usage of rigorous mathematical programming approaches based on increasingly general problem representations such as the Resource-Task Network (RTN) Framework recently proposed by Pantelides (1004). These approaches often require the solution of large optimisation problems, the size of which increases with the length of the time horizon being considered. For medium-term scheduling problems typically considering time scales ranging from one month to a year, the solution via the direct application of the mathematical programming techniques mentioned above is very often impossible with the currently available computer hardware and solution methods. This paper presents three "rolling horizon" algorithms that are formally based on the rigorous aggregated RTN formulation presented by Wilkinson (1996).