In 2011 WHO conditionally recommended the use of at least 36 months of isoniazid preventive therapy (IPT) (as a proxy for lifelong or continuous treatment) for people living with HIV in high TB-prevalence and transmission settings. The evidence of the benefits and harms of 36-month IPT compared to 6-month IPT was reassessed and the following recommendation was made: “In resource-constrained settings with high TB incidence and transmission, adults and adolescents living with HIV, who have an unknown or positive tuberculin skin test (TST) status and among whom active TB disease has been safely ruled out, should receive at least 36 months of IPT. IPT should be given to such individuals regardless of whether or not they are receiving ART. IPT should also be given irrespective of the degree of immunosuppression, history of previous TB treatment, and pregnancy.” The quality of evidence was rated as low. The conditionality of the recommendation was primarily due to the fact that implementation of continuous IPT requires considerations of TB epidemiology, health infrastructure, programmatic priorities and patient adherence.