The present study has been conducted with the purpose of exploring the relationship between EDBI staff's General English proficiency and their technical English Writing as well as the way each ESBP and GE courses affect their writing skill. The kind of the study is quasi-experimental with pre-test and post-test, being conducted among EDBI staff in Tehran Branches and Headquarters. In data collection two standard tests were used, namely Preliminary English Test (PET) for homogenous subjects, and also the level of their GE progress at the end of the treatment, and Business English Certificates (BEC) test Level B1, to measure their technical writing skill with appropriate validity and reliability. The findings indicate that: 1) there was a correlation between subjects’ general English proficiency and their business writing proficiency; 2) teaching writing of banking texts significantly improved EDBI staff’s General English; 3) teaching writing of banking could significantly improve EDBI staff’s Business English proficiency; 4) teaching writing of banking could significantly improve EDBI staff’s Business English proficiency more than GE proficiency.
