It's very common in Taiwan to use ceramic tiles as an external wall material. Even the nature of ceramic tile is stable, the deterioration such as chaps and peeling still occur on external walls, which should face the tough conditions like sunshine, raining, etc. In this study, the conditions of deterioration of ceramic tiles on exterior walls were clarified by the field investigation of townhouse, built during 1971~1990, in Kaohsiung City. After analyzing and comparing the deterioration of the above cases, the conditions of deterioration of external wall tiles, used on townhouses, were found as follows: 1. The main deterioration of Mosaic tiles is rust stains, cracking and flaking. 2. The main deterioration of square tiles is rust stains, efflorescence and cracking. 3. The main deterioration of rectangular tiles is rust stains, cracking and flaking.