Feedback is an important skill and a valuable part of any language course. The term feedback has been used by various scholars to refer to both negative as well as positive error treatment in both natural settings and the instructional setting. Some researchers have raised objections to corrective use and have pointed out that it is unhelpful or even harmful for students’ writing development. Yet others seem to have established evidence in support of corrective feedback. Nevertheless, very few studies have conducted an experiment on the effectiveness in terms of accuracy on business letter writing. This quasi-experimental study involving 63 senior students in two sections of business English classroom at an international university in Thailand were divided into two groups. Each group received one type of feedback. The group that received direct corrective feedback perceived it positively hence they showed better improvement when compared to the group that received indirect corrective feedback which was negatively perceived. Further investigation on different writing types and different native language (L1) background would contribute more to the field’s literature as more debate on the effectiveness of written corrective feedback will still need further research to address many unanswered questions.