In Africa, particularly in Gabon, the monopoly in the telecommunication sector led in the mid 90s, to a substantial decrease in demand for telecommunication services. This resulted in a drop in the telecommunication revenues and a decrease in the Gabonese Gross Domestic Product (GDP). Studying the opening up of the telecommunication sector in Gabon meant evaluating the theoretical reasons that have caused the Gabonese government to implement a regulated competition in this sector. What is more, the Cost Benefit Analysis (CBA), which is a research appraisal tool, was used to measure the monetary and non-monetary impact of a regulated competition on the economy.In order to conduct this study, information were collected through the different operators of the telecommunication sector and the department of economy. The results obtained served to draw the conclusions that the opening of the telecommunication sector in Gabon has benefited to the household, the telephony operators and the Gabonese government.