Background: Contacts over 35 years old are generally excluded from the treatment of latent tuberculosis infection, because of its high basal tuberculin skin test (TST) positivity and the risk of hepatotoxicity. It is revealed in the previous study con-ducted in Korea, that the risk of latent tuberculosis infection is increased if closely in contact with tuberculosis patients. In this study, based on a previous Korean study, we tried to find the factors significantly increase the risk of latent tuberculosis infection in contacts over 35 years old. Method: 41 contacts of pulmonary tuberculosis patients underwent TST, interferon-gamma release assay (IGRA), and chest radiography. The TST results were considered positive with an induration of 10 mm or more. TST positive or IGRA positive were regarded as latent tuberculosis infection. A standardized questionnaire was used to assess risk factors associated with tuberculosis infection. Result: Latent tuberculosis infection was diagnosed in 31 of 41 contacts of tuberculosis patients (75.6%). There was no differ-ence in the prevalence of latent tuberculosis infection, according to the strength of the contact or contact period. In addition, according to the factors associated with the virulence of the tuberculosis patients, there was no difference in the rate of latent tuberculosis infection. Conclusion: The risk of latent tuberculosis infection seemed not to be significantly increased with the strength of the contact, the contact period, or the virulence factor of tuberculosis patient among contacts over 35 years old in our study.