Abstract: Competitiveness in the banking industry has made the task of raising loanable funds more difficult as customer needs have become more complex. This study discusses the use of demographic segmentation in defining customer needs, customer profile, preferred transaction and channel from each segment using data mining techniques. Unstructured interviews conducted with the management team and BI department in the head office of a big private bank in Indonesia. Data were collected from the data warehouse and analyzed using Microsoft Excel. Although, there are more advanced segmentation techniques available this research used demographic segmentation to find insight of the product and services already offered to existing customers. The findings were further interpreted to refine the products and service development and also improve the marketing promotion.