Background: Tuberculosis is one of the most important diseases with annually 8 million new cases worldwide. The purpose of this study was to investigate the risk factors for tuberculosis (TB) infection.

Methods: In this descriptive study performed in Health center of Maznadaran province during 2010-2011, 183 patients with pulmonary and extrapulmonary TB infection were recruited. After measuring fasting blood sugar, and human immunodeficiency virus (HIV) antibodies, history of smoking was taken by using a questionnaire.

Results: The mean age of the participants was 46.8±19.8 years. The most common risk factor was diabetes and the lowest was HIV infection. Moreover, the prevalence of diabetes in women compared with that of men (OR=0.19, 95% CI=0.07±0.46) and smoking in men compared with women (OR=12.4, 95% CI=2.8±54.4, P<0.05) had statistically significant differences (P<0.05).

Conclusion: The results of this research show that diabetes and smoking could be risk factors for tuberculosis infection. It is concluded that, in case of respiratory symptoms in patients with diabetes and smoking, tuberculosis can be considered as an important differential diagnosis.