This article reviews the current status of the employment of the isotope effect in solids. Diffusion, self-diffusion processes with different isotopes in pure materials and heterostructures ( quantum wells), neutron transmutation doping of different semiconducting crystals, optical fiber as well as use isotope-mixed crystals ( C, LiH) as the generator of the coherent radiation in the ultraviolet range of the spectrum are the main modern applications of isotope science and engineering. There are briefly discussed the other future applications including modern personal computer, isotope-based quantum computer as well as information storage. We hope to give sufficient references to published work so that the interested reader can easily find the primary literature sources to this rapidly expanding field of solid state physics. (C) 2003 Kluwer Academic Publishers.