This article is concerned with the introduction of electronic control devices (‘numerical controls’) in machine tools. This has provided substantial benefits to firms in that it saves both capital and labour, improves product quality and reduces the time required to bring new products onto the market. Whilst these advantages may appear to benefit developed countries disproportionately, the most significant benefit conferred is probably in relation to the saving of skilled labour. Since skilled labour is the major element in the developed countries' comparative advantage, it is likely that the diffusion ot these machine tools will move comparative advantage in favour of the newly industrialising countries (NICs). However, the article concludes with the warning that advances in automation technology will probably reduce this temporary shift.