Despite years of HIV testing and other interventions, Lesotho continues to experience an incredibly high HIV burden. Prevalence of HIV among children ages 0-14 years is at 2.1% and 25.6% among adults ages 15-59 years. Among adults living with HIV, 77.2% know their status, 90.2% of those with known HIV positive status are currently receiving ART and 88.3% are virally suppressed. In order to identify adults, adolescents and children at high risk of HIV infection, Population Services International (PSI)/Lesotho with support from the Centers for Disease Control and Prevention (CDC) introduced the HIV Index testing model in 2015. PLHIV recruited for index testing, were accessed through health facilities and community testing at PSI New Start channels in five districts. Consenting index clients received home visits for HIV testing of their biological children and sexual partners with unknown status. Routine monitoring of data gathered between May 2015 and November 2017 was analyzed to assess feasibility of this approach. For HIV index testing, 49.2% of children below 15 years and 37.3% of adolescents ages 15-19 were first time testers while 18.8% of all adults aged 20 years and above tested were testing for the first time. Higher HIV positivity rates among clients tested through the HIV index testing model across all age groups in comparison to other HIV testing models were statistically significant. Among children ages 2-14 years, the HIV positivity rate was 1.4%, adolescents ages 15-19 years had a positivity rate of 2.4% and adults ages 20 years and above had a positivity rate of 17.6%. Linkage rates of 92%, 73% and 72% for children, adolescents and adults, respectively, achieved with the HIV index testing model were higher than linkage rates observed with other HIV testing models. Results indicate that testing of biological children and sexual partners utilizing the HIV index testing model can be viable to identify and link children, adolescents and adults into care and treatment.