OBJECTIVE: To discuss the application of logic to pattern differentiation for treatment in Traditional Chinese Medicine (TCM). METHODS: Comparing logic reasoning of syllogism with the logical thinking ofTCM pattern differentiation for treatment. RESULTS:TCM logical thinking depends on symbolic and intuitive judgment with abstractive reasoning integrated into the process. Although it lacks quantitative measurement, it pays great attention to the comprehensive analysis of a disease's cause and its development patterns to get insight into the essence of illness. CONCLUSION: TCM diagnosis reasoning methodmay lack rigorousness, continuity, systematic induction and deduction, but its logical thinking still can attain its goal following a process with rigorous, regulated and scientific formal logic.