The paper aims to estimate the level of informal employment in Romania and to identify the main informality poles at county level using the labour approach for the period 2000-2013. In order to do that, administrative data from Labour force balance were used providing the official labour use side in the labour market. The empirical approach is based on Crnkovic-Pozaic(1999) and Svec (2009) for Croatia, Nastav ?i Bojnec (2007) for Slovenia. The fundamental hypothesis of the labour approach is that the changes in official population activity rates are caused by factors related to the underground economy. One can suppose that the decreasing of this rate could indicate the existence of a flow of population from official to unofficial economy. The analysis based on development regions revealed that Nord-East, South-West-Oltenia and East-South and South-Muntenia are poles of informality at the level of 2013. At county level, Maramures, Bihor, Salaj, Harghita, Covasna, Alba, Botosani, Neamt, Suceava, Gala?i, Braila, Giurgiu, Calarasi, Ilfov, Gorj ?i Caras-Severin are the main poles of informality at local level for the year 2013. Given results are approximatively and show the level of Romanian shadow economy which is presumably underestimated. These phenomena occur because of available statistics and method limitations.