For researchers studying intra-industry trade and the methodology involved in measuring the phenomenon one of the most important driving forces was the assumption that the creation of economic integration would lead to lower adjustment costs than were characteristic of the traditional commercial model. Another result was that - according to empirical data - intra-industry trade would receive a strong incentive from liberalisation, and that the accompanying adjustment costs would be lower than in cases there there was specialisation bewteen branches. In so far as this is demonstrable, proponents of attempts to achieve general integration offered a convenient weapon to their opponenets, who consistently argued back that it was precisely the difficult application of this process and its drawn-out and 'painful' nature that caused high costs. The first part of the article is devoted to a discussion of this debate, while the second part focuses on the role intra-industry trade plays in harmonisation with business cycles. The article shows that an examination of the intensity and dynamism of intra-industry trade allows a much more sophisticated analysis of a country's position in the world economy than is usually possible.