The last decades have seen a proliferation of economic studies that have compared the economic performance of organic and non-organic farming systems. Several criticisms were formulated questioning the validity of such comparisons, partly because of the inherent difference between the two systems (in terms of complexity, diversity and objectives other than yield maximalisation), and partly due to the difficulty in excluding ’non-system’ determined factors that also have an influence on profitability. Furthermore, the adequate selection of a reference group for comparisons has proved to be fundamental for relative profitability: which organic farms are put on the profit measuring scale by researchers with which conventional farms determine the outcome. The list of profitability studies compiled in this paper involve more than 50 different cases, mostly from U.S.A, where several universities started long-term experimental field studies in the eighties and from European countries. Just over a dozen shorter-term studies have been collected from developing countries on high-value export crops. Most studies have used a casestudy approach selecting between five up to hundreds of farms for the collection of data on farm economics.