The Rice Microarray Opening Site is a database of comprehensive information for Rice Microarray Project (April 1999 - March 2003). Microarray is the powerful tool for understanding comprehensive gene expression at genome-wide level (for details, refer to the Technical Background Section). By using this system, it has become possible to isolate the genes quickly that confer resistances or are responsive to cold temperature, drought, unsuitable soil condition, insect pest and disease, etc. It has become possible by using this system to begin to quickly isolate the genes that confer such resistance. Also it has become possible to isolate which genes are expressed in particular tissues and organs.