The aim of this chapter is to describe in detail the advances in polyethylene reinforced with lignocellulosic material. Indeed, the successful employment of natural based materials to reinforce/improve the properties of polyolefins has been growing in a wide range of applications. Firstly, basic concepts and terminology adopted in the lignocellulosic composite materials are reviewed. The objective is to bring the readerâ s attention to important issues that must to be taken into account when working in this subject as well as by providing the most appropriate references for those with interest to delve into the topic. In the context of polyethylene lignocellulosic composites, ongoing research is then summarised mainly focussing on (i) the main aspects related to the selection of the commonly used lignocellulosic materials and the potential of its main chemical constituents, (ii) the principal methods used for the improvement of interfacial adhesion and (iii) the main adopted processing routes and the composite properties. Finally, applications, new challenges and opportunities of these polyethylene-lignocellulosic composites are also discussed.