Transgenic cotton plants were amongst the first genetically modified (GM) plants to be released on the market in 1995/1996. Since then, the acreage devoted to GM cotton worldwide has increased dramatically, reaching 5.3 million hectares in the year 2000. This figure represents 16% of the world cotton acreage. In the United States of America, GM cotton represents more than 70% of the national cotton acreage, whereas in continental China, the proportion of transgenic cotton is approximately 10%. Other countries, such as Australia, Argentina, Mexico, and South Africa have already adopted this technology, while others are awaiting a proper legislation (or modifications thereof) to introduce these plants. Many more countries are in the process of evaluating GM cotton in the field. The rapid growth in the acreage devoted to GM cotton (from 700-800 000 ha in 1996 to more than 5 million ha in 2000) seems to indicate than farmers adopting this technology must somehow benefit from its use. The fact that these varieties have been grown on a large scale for 5 years allows a preliminary analysis of their financial and ecological impact. Despite important variations from year to year and from place to place, adopters of the GM technology seem to have benefited financially from transgenic varieties. The issue of GM plants is in the midst of a passionate debate in particular in Europe (but also in other countries), and various points regarding this technology have been raised. These include, but are not restricted to, public health, the impact on the environment (the development of toxin-resistant insects, (trans) gene flow...), as well as socio-economical issues. It is probable that the areas devoted to GM cotton will grow within the next few years through the opening of new markets, as well as through a more divers offer. Indeed, a number of companies and institutions are presently testing new transgenic cotton plants whose agronomic or technological properties have been modified