Polyolefins are still protagonist of an exciting innovation, due to a continuous development of new catalysts, processes and products. The positive solutions given by polyolefins to the environmental and energetic issues are among the factors responsible for their success. The most relevant breakthrough occurred in the last years is the discovery of metallocenes, and more in general, of single centre catalysts. They are, in most cases, highly active catalysts and are already employed on the industrial scale for the preparation of both "drop-in" products with improved properties, and of totally new materials.