This study utilizes GDP quarterly data to investigate the trough of the eighth business cycle in Taiwan and to analyze the cause of its formation. Monthly reference cycle data and the Markov Switching Model are used to identify the turning point of the cycle. From our analyses, we define the trough of the eighth cycles as located at December (or the fourth quarter) of 1995. This result is the same as that of a previous study by one of the present authors. However, the result is different from the Council of Economic Development and Planning dating which was three months (or a quarter) late. The difference may be attributed to defective data on the service sector and on the domestic demand that were complied as the leading and coincident indicators.