Abstract The market environment of Mobile Phone Industry has had rapid change in the past decade. It is almost same important to gain the loyalty of existing customers as to gain the new customers in the current competitive environment. For many companies in this industry, Customer Relationship Management has been become a significant issue in their strategies. This research is based on the concept of Customer Relationship Management. The purposes of this research are to probe the performance of Customer Retention Programs and the churn reason in mobile phone industry. The research datum were collected from TAT Corp.(TransAsia Telecommunications) including Customer Retention Programs as ¡§Second Honeymoon Program¡¨, ¡§New Second Honeymoon Program¡¨ and ¡§Talking Reward Program¡¨ and a survey from the customers who had been deactivated in February and March of the year 2002. The analysis of the retention programs show significantly relevant on AGE, GENDER, CUSTOMER LEVELS, TENURE, and RATE PLAN factors. The inspection results of survey datum in the churn reasons are explained individually. The suggestions are made after discussing the policies and strategies of TAT Corp.