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In this report the different methods of pulsed field gel electrophoresis and the parameters such as electrical field geometries, field angles, field strengths, type of buffer and its ionic strength, type of gel and its concentration, and the effect of temperature were considered. Among them a technique called "Contour Clamped Homogeneous Electric Field" was chosen for further studies. Based on this technique, a pulsed field gel electrophoresis system was designed and constructed. Finally, the ability of system for separation of large DNA molecules was examined. Using this system, we were able to separate the compositions of Saccharomyces serevisiae in the molecular weight range of 90 Kbp to 2.2 Mbp.