The aim of this study was to describe the knowledge, attitudes and smoking behavior among doctors at Mahosot University Hospital in Lao PDR. A cross-sectional, descriptive study used a self-administered anonymous questionnaire. The study population comprised 164 doctors. Answers were retrieved from 151 (92%) of the doctors. The prevalence of smoking among male doctors was 35%, 16% smoked daily and 19% occasionally. None of the female doctors reported to have ever smoked. Out of the five diseases related to smoking, 5% of the doctors recognized all and 10% recognized only one. Doctors were significantly more likely to advise patients with symptoms related to smoking. However, approximately one in two doctors reported that they did not always counsel smokers with severe smoking related symptoms to stop smoking. Almost all doctors, independent of smoking behavior, perceived tobacco prevention to be important. The findings indicate a lack of comprehensive knowledge on tobacco related issues. Most doctors expressed a positive attitude towards tobacco prevention. An effort is needed to get doctors in Lao PDR to stop smoking engage in smoking assation support.