Modern customs administrations aim to both facilitate legal trade and combat fraud. To meet this dual objective, many customs administrations in developing countries must give risk management a highly prominent role. In this context of modernization, this article first provides stylized facts on the performance of the customs controls carried out at the Gabon border. Then, we compare Gabon's granular import customs data with international trade statistics. Based on this comparison, we identify undetected fraud and develop a methodology to target ex post audits. Finally, we define indicators to monitor the performance of customs valuation controls. To improve their performance, we show that customs in developing countries should rely more on data analytics, notably via the implementation of simple statistical tools and the diversification of their sources of information. .