English has played a significant role in world communication especially in commerce and international trade. With modern information technology, English, used by business communicators from different countries, has become a communication tool, actually, an international language for global communication both in speaking and writing. In Thailand, in particular, there are some features of the written business discourse of the Thai workplace which use English in their written communication such as e-mails, memos and other correspondence, integral to their business operation. In this study, samples of written business communication in English were collected from the Thai workplace in Bangkok. They were examined in terms of the use of English at the linguistic and discourse levels. A questionnaire and interviews were conducted to find explanation in depth about the nature of communication and possible problems. The findings show despite a large number of errors in the samples, Thai business communicators rarely had problems with their business dealings since they made use of communication strategies including follow-ups.