In view of the importance of InP as a new material that is especially appropriate for very high frequency applications, a Monte Carlo method has been applied to analyse its electron transport properties at very high electric fields, using a five-valley model for the conduction band. Two of these valleys (X₇, Gamma ₇*) have not been used in previous simulations. The model is shown to be valid too for low fields. The high field results point to the great importance of the X₇ valley (higher than in GaAs), determinant in all transport phenomena.