Several decades of market opening has become a characteristic of network industries. Its main hindrances and aids has come into sight during this period. There is a need now to evaluate the process of market opening and to assess the steps to be taken. Market opening is usually measured by changes in competition, market structure, entry conditions, separation of vertically integrated firms and in cost and prices. British, Australian, US and EU experiences are covered in this study followed by the measures of Hungarian market opening.