In April 2000, the American Thoracic Society published guidelines for targeted tuberculin testing and the treatment of latent tuberculosis infection (LTBI) (1). These guidelines are a joint statement of the American Thoracic Society and the Centers for Disease Control and Prevention, and were endorsed by both the Infectious Diseases Society of America and the American Academy of Pediatrics. Similar recommendations were published by the Infectious Diseases Society of America in its guidelines for the treatment of tuberculosis (TB) (2). These updated guidelines were developed in recognition of the importance of treating LTBI as one component of eliminating TB in the United States ‐ a goal reiterated in 1999 by the Advisory Council for the Elimination of Tuberculosis (3) ‐ but also realizing the differing risks and benefits of treatment for patients based on their individual risks of developing active disease or drug toxicity (4). The 2000 edition of the Canadian Tuberculosis Standardsprovided similar recommendations for the treatment of LTBI (formerly known as chemoprophylaxis) and reminded us of the two major Canadian TB elimination initiatives: the National Tuberculosis Elimination Strategy (Medical Services Branch, 1992), with the aim of eliminating TB in First Nations people by 2010, and the National Consensus Conference on Tuberculosis (Health Canada, 1997), with an interim goal of a 5% reduction in the number of TB cases each year in Canada (5). Given the recent publication of the American guidelines and the updated Canadian Tuberculosis Standards (Fifth Edition), it was considered timely to remind readers of the evidence supporting the use of antituberculous chemotherapy in the treatment of latent infection.