Experimental determination of grain structure evolution in an Al-Mg-Si alloy (EN AW-6082) during hot forward extrusion is investigated. In order to observe the development of grains and their orientation under severe plastic deformation at elevated temperatures, a miniature forward extrusion setup was designed. The extrusion butt was quenched immediately after extrusion to avoid secondary recrystallization effects like static recrystallization and grain growth, thereby preserving the evolution of grain structure during deformation. The material flow within the extruded billet was determined by finite element simulations. Microscopic analysis over the material flow lines and finite element analyses allowed the observation and prediction of the dynamic evolution of grains at an arbitrary material point undergoing plastic deformation. The results provide a database for the development material models for predicting and simulating the evolution of microstructure during the hot deformation of EN AW-6082 alloy.