This research focuses on the measurement of the non-observed economic activities by sector of South Africa for the 2011 and 2016 calendar years. The purpose of the research is to determine whether the current GDP as estimated by Statistics South Africa is under- or overestimated when considering the non-observed economy. The research is based on the 2008 System of National Accounts as it determines the guidelines, definitions and characteristics of the “Non-observed economy (NOE)” sector and it allows national accountants to use/supplement the research in the estimates of the GDP. This research follows a quantitative methodology where several surveys of Statistics South Africa are used. Where lack of data exists, some administrative data is used regarding the illegal activities. The findings of the research is that the total economy of South Africa is underestimated when taking into account the NOE activities. / Economics / M. Com. (Economics)