Until today, herbicide-tolerant (HT) transgenic crops have been the most widely used type of transgenic crops. In 2008, worldwide, 63% of all agricultural land devoted to transgenic crops involved HT transgenic ones, and the percentage was higher (85%) when the herbicide-tolerant trait was stacked with another. In addition, other HT crops are foreseen within the next five years if we are to believe the "pipeline" of the companies involved along with field trials. However, herbicide-tolerant crops have been criticized, particularly in Europe, because of the type of trait introduced: herbicide tolerance. Indeed, this trait leads the crops to depend on a herbicide (generally glyphosate) instead of freeing them from some pesticides through a better use of their biological capacities and a valorisation of life processes as biotechnology was expected to do. Therefore, how can we explain the widespread use of HT transgenic crops and what are their fallouts? At first the paper presents the extent of surface areas dedicated to these crops and the factors that have led to the development of these herbicide-tolerant crops. Then, the case of glyphosate-tolerant soybeans in the USA is studied in more detail. Its agro-environmental impacts, particularly with regard to trends in the use of herbicides, are analyzed. Thirdly, we address the factors of adoption, economic performance, benefits, and drawbacks of this soybean as well as its prospects. Finally, the conclusion questions the contribution of HT soybean to more sustainable agriculture.