In this paper we explore an important class of supply contract called the Rolling Horizon Planning (RHP) Contracts in a single supplier and a single retailer system. We illustrate how RHP provides flexibility for a buyer to respond to uncertain market changes. Under such a contract a buyer has to commit requirements for a T-period rolling horizon with N-period information of the forecast demands. The buyer can also update the ordering quantities for the current period and future periods by paying the reorder or cancellation cost. We develop a general non-linear programming model for the study of the RHP contract. We also show that the optimal replenishment strategy follows an order-up-to policy. Numerical results reflect the impact of the length of forecasting periods on buyer's average cost and order quantities.