This article analyzes Brazilian telecommunications companies after privatization, from 1999-2007, to compare reasons for best and worst economic performances. Main indexes showed sector growth after privatization in 1998. Profitability rankings based on criteria by Matarazzo (1997) were studied as well as a subsequent review of selected multiple cases of best and worst performances. Reasons for best performance were a strategy to reduce costs and control intangible assets, implemented in a strong organizational culture with a focus on improving financial results. Worst performance was due to mistaken strategies related to the market technological standard and investment in indexes of questionable profitability, such as market share. Telefon...