OSIPE - a tool for scientific programming in FORTRAN. FORTRAN tools have been designed to support well-structures, modular, route-independent and easily interfaceable programming. This set of tools, which creates a kind of low-level object-oriented programming environment, is refered to as OSIPE (Open Structured Interfaceable Programming Environment). Its main role is to transform meaningful FORTRAN variables into Objects which are linked via “created-by” relationships. Two programs, written in the OSIPE environment, an ab initio electronic structure code, MUNGAUSS, and a novel implementation of a quantum chemical solvent effect theory, SOLVENT, are briefly described. Efficient tools are provided to restructure existing FORTRAN codes and make them compatible with the OSIPE environment.