Ab initio configuration interaction (CI) potential function calculated from a 6-311G** basis set at a MP2 level of theory is used to compute the vibrational energy levels of methyleneimine CH2NH between 2800 and 3200 cm(-1). The most important configurations selected by an iterative process by means of a variational perturbational method are diagonalized. Results show a perfect agreement with the most reliable experimental values and predict the; nu(5) + nu(6), nu(4) + nu(6), and nu(4) + nu(5) unobserved combinations.