Slow-mode waves have been observed to appear frequently in front of the dayside magnetopause. It is found based on two-dimensional global MHD simulations that slow-mode waves are generated through the interaction between the bow shock and various MHD waves (fast-mode, Alfven-mode, or slow-mode waves) in the upstream solar wind. The generated slow-mode waves stay in front of the magnetopause for a long time (over 15 minutes) before the wave energy is convected away tailward. Since various waves are often present in the solar wind, this mechanism may lead to the frequent appearance of slow-mode waves in front of the magnetopause. ¿ American Geophysical Union 1994