The present work employs the self-consistent tight binding linear muffin-tin orbital method to calculate the electronic structure and the relative stabilities of LaP and LaAs at high pressures in the rocksalt, primitive tetragonal and CsCl structures. At compressed volumes, these compounds favour the tetragonal phase over the CsCl phase, which can be seen from the total energy curves. The transition from rocksalt to tetragonal occurs around 18, 11.2 GPa in the case of LaP and LaAs, respectively. The ground state properties of these systems such as bulk modulus and lattice constant are in good agreement with the experimental results. The band structure and density of states are plotted for both B1 and tetragonal phase and are compared with the available literature. © 2002 Elsevier Science B.V. All rights reserved.