A method for on-line prediction of the power distribution within boiling water reactors has been developed. The prediction procedure consists of two parts: the first is to estimate the present Traversing In-Core Probe (TIP) readings using Local Power Range Monitors (LPRM) readings, which is required to give the initial condition of the predictional calculation; the second is to predict the TIP readings after motion of a control rod. Results of numerical experiments show that the TIP readings are predicted, with reasonable accuracy, within a short computer time and a small core memory. It is felt that this method is suitable for on-line computer application.