This article examines the variations in mean technical efficiency estimates in organic agriculture and the factors that explain the observed variations. A three-stage process was employed in data collection. Firstly, journals on organic agriculture and related disciplines were identified and searched. Secondly, several publishers’ websites and databases, namely Cambridge Journals, Elsevier, Emerald, Oxford University Press, Sage, Taylor and Francis, and Wiley, among others, were covered. Databases included AgEcon Search, CAB Abstracts, DOAJ, EBSCOhost, Google Scholar and ScienceDirect. Thirdly, the reference lists of studies found in the first and second stages were searched to identify additional literature. In all, 42 studies constituting 109 observations published in the period 2002-2014 were found. Unlike existing literature on technical efficiency quantitative reviews in agriculture, this article employs a battery of tests to select the appropriate solution for multiple observations from the same primary study, as well as the appropriate functional form for the selected fractional regression model. The mean technical efficiency of organic agriculture for the period of study and the effects of other study characteristics are thoroughly discussed.