The photosensitive Belousov-Zhabotinsky (BZ) reaction with Ru(bpy)(3)(2+) catalyst has been used to study wave propagation and annihilation at the boundaries of excitable and inhibitory regions of an active medium. Depending on the degree of excitability of the two areas, waves can either penetrate into the inhibitory region or collapse in the excitable zone. The experimental trend can be reproduced semiquantitatively with a numerical calculation based on the three-variable Oregonator model modified for the light sensitivity of the reaction. These results suggest that the photosensitive BZ medium may be a useful model for studying the effects of the geometric arrangements between areas of different excitability.