This article takes advantage of new political demand at the government’s highest level to focus on measurement of the informal economy in Vietnam from a statistical perspective. The main challenges, concepts and definitions regarding the informal economy within the framework of the non-observed economy are reviewed. A discussion of alternative methodologies for measuring the informal sector, in general and their application to Vietnam, is presented. As the two main strategies for measuring the informal sector have been conducted in parallel since 2007, this gives a unique opportunity to compare the two approaches. Based on past experiences, some recommendations for designing an improved system are made. A review is conducted of the illustrative empirical results, both on the labour market and the national accounts, and thoughts on the challenges ahead are offered.