An experimental study on the microstructure development and stress-strain behavior during high temperature deformation of aluminum (Al) single crystals was made by using X-ray Laue technique and the electron backscatter pattern (EBSP) technique. The main purpose was to clarify the process of dynamic recrystallization (DRX). The measured stress-strain curves with large stress peaks and the new Lane spots without streaks at around the stress peaks confirmed the occurrence of DRX in Al single crystals with initial compression axis <111>, <011> or <001>. Crystallographic analysis by the Laue technique and EBSP technique show that the DRX grain and the matrix have an <121> axis in common in the <111> crystal, an <101> axsis in the <011> and <001> crystals. For the <111> crystal, the unrecrystallized region near the DRX grain consists of subgrains adjoined each other with <112> tilt boundaries and the size of subgrains becomes smaller and the misfit at subgrain boundaries becomes larger as the DRX grain boundaries are approached. These results suggest that DRX grains are nucleated through the development of subgrains.