The study proposed, designed and evaluated a methodology for developing an English course for business oral communication of customer-services staff in international banks by translating the actual learners' needs into course development. The objectives of the study were to identify learners' needs and issues in using English in order to develop a specific English course, and, to evaluate the effectiveness of the course whether it could enhance learners' English oral proficiency, banking vocabulary knowledge and self-confidence in speaking English. The instruments for needs analysis included 174 questionnaires, 14 interviews with customer-services staffs in international banks, 6 interviews with the management in charge and 22 site observations. The course has been validated by 5 experts and the piloted with a group of learner having similar characteristics of the main study group. Both quantitative data were collected for course evaluation. Instruments for quantitative analysis included an oral/speaking test, the use of observed banking vocabulary in context measured by a number of observed vocabulary items used during the oral pre- and post-tests self-assessment of learners' confidence levels and teacher's class observations. Each test and assessment was performed twice i.e. at the beginning of the course and at the end of the course. The teacher's class observation regarding participants' confidence level was conducted in every class. Instruments for qualitative analysis were teacher's log and learners' logs. Both teacher and learners kept records in their logs at the end of each class. The analytical results from t-test revealed that learners gained higher levels of English oral proficiency, increased use of observed banking vocabulary in context, and increased confidence in speaking English at a significant level of 0.05. It was also observed that motivation had a significant role in enabling learners to achieve higher levels of English proficiency. Learners and their management demonstrated positive attitudes towards the learning and the course.