The design principles of the IPMLO, a modularly structured library of FORTRAN subroutines for large scale linear optimization with interior point methods are addressed. The objective of the library is to provide the base for the development and experiments with the new attractive approaches that apply interior point methods for solving linear programming problems. An example application of it for the implementation of the primal-dual logarithmic barrier interior point method of K. A. McShane, C. L. Monma and D. Shanno [ORSA J. Comput. 1, No. 2, 70-83 (1989; Zbl 0752.90047)] is described. The preliminary computational results of the code’s application to the solution of medium scale LP test problems from the Netlib collection are given and the comparison with the implementation of the simplex method is made