In the study of vascular biology, analyses of endothelial cells (EC) and smooth muscle cells (SMC) are very important. The mouse is a critical model for research, however, the isolation of primary EC from murine aorta is considered difficult. Previously reported procedures for the isolation of EC have required magnetic beads, or Fluorescence Activated Cell Sorting (FACS) to purify the cells. In addition, these procedures were applied to the heart, eyeball, or lung, not the aorta. Therefore we developed a simple method of isolating EC or SMC from the murine aorta without the need for any special equipment. To verify the purity of the cell culture, we performed both an immunofluorescence study and a DNA microarray analysis. The immunofluorescence study demonstrated specific expression of PECAM-1 in isolated EC cultures. In contrast, the isolated SMC didn’t exhibit PECAM-1, but rather, smooth muscle actin. The DNA microarray analysis demonstrated the expression of EC (16 genes) or SMC (5 genes) specific genes in each cell. This is due to the fact that pure EC or SMC can be isolated from the aorta, without the use of any special equipment. These results suggest that this method should be particularly useful for vascular biological research. J Atheroscler Thromb, 2005; 12: 138–142.