The 2030 Agenda identifies the reduction of IFFs as a priority area, as reflected in target 16.4: 'by 2030, significantly reduce illicit financial flows and arms flows, strengthen the recovery and return of stolen assets and combat all forms of organised crime'. This target is critical for financing efforts to achieve SDGs. IFFs were also identified as a global priority in the Addis Ababa Action Agenda (United Nations, 2015) on financing for development which calls for a redoubling of efforts to substantially reduce IFFs, with a view to eventually eliminating them. Regardless of its importance, data on indicator 16.4.1, 'total value of inward and outward illicit financial flows', are not yet reported as part of the SDG indicator framework (United Nations, 2017b). Comparable and reliable statistics on IFFs are needed to shed light on the activities, sectors and channels most prone to illicit finance, pointing to where actions should be undertaken as a priority to curb these flows. This paper was prepared based on process and lessons learned within the United Nations Development Account project on 'Defining, estimating and disseminating statistics on illicit financial flows in Africa', implemented by United Nations Economic Commission for Africa (UNECA) and United Nations Conference on Trade and Development (UNCTAD). Pilot testing by the following countries provided valuable feedback in future refinement of the methods: Angola, Benin, Burkina Faso, Gabon, Ghana, Mozambique, Namibia, Nigeria, Senegal, South Africa, and Zambia