Abstract: Objective To observe the adverse reactions of Cycloserine in the treatment of patients with multi-drug resistant pulmonary tuberculosis, and provide the basis for clinical safe medication.Methods To review the use of Cycloserine in the treatment of patients with multi-drug resistant pulmonary tuberculosis in our hospital, summarize the types of adverse reactions, the occurrence time and the processing results. The total number of patients was 61,and the number of patients with multi-drug resistant pulmonary tuberculosis treated with Cycloserine was 50 cases. The patients were aged between 18 and 78 years old, and the median age was 42.5 years.Results Up to 84.0% (42/50) of patients can complete the 24-months treatment course. Adverse reactions occurred in 8 cases, most of them occurred in the nervous and mental aspects. The incidence rate of adverse reactions was 16.0% (8/50), and the 8 patients discontinued the use of Cycloserine after the adverse reactions occur with the discontinuation rate of 16.0%. Those adverse reactions were all relieved after stopping the drug.Conclusion Cycloserine is a relatively safe drug for the treatment of multi-drug resistant tuberculosis. But in the course of using Cycloserine, need to be alert to the nervous and mental symptoms.