Chapter 7 gives an idea of computation of principal characteristics of the photonic crystal fibers (PCF). Similarities and distinctions between PCF and conventional optical fibers are considered. The first part of the chapter deals with theoretical relations and characteristics of conventional fibers. The second part gives classification and characteristics computation of PhC fibers. The chapter gives detailed analysis of the index-guided photonic crystal fibers, as well as PBG fibers. The computations technique for their eigen-states and field distribution are demonstrated and analysis of results is carried out. At the end of the chapter, the example of original Matlab-code for computation of fundamental mode distribution in microstructured fiber by means of PWE method is presented and several problems and questions for self-training are given.