Financial sector development should be positively judged as it improves effectiveness of the financial system and widens the savings and credit products offer, which improves long term economic growth. In this view, and with reference to the pressures of the modernisation and development processes related to globalisation, it is interesting to know if the Mauritanian financial system can bear the risk of opening to other countries and of the global integration and what are the conditions for its contribution to the country economic growth. This is the purpose of this article. The analysis of Mauritanian economy from 1985 to 2004 shows a marginal positive effect of banking sector on economic growth. This weak contribution can be explained by the absence of a dynamic banking system, able to transform available financial resources in profitable projects. Financial openness is an opportunity for developing countries to improve their funding but the recent financial crises have demonstrated the need to mobilise local resources to foster healthy economic growth less dependent on foreign funds.