['Patients with newly diagnosed HIV may be part of social networks with elevated prevalence of undiagnosed HIV infection. Social network recruitment by persons with newly diagnosed HIV may efficiently identify undiagnosed cases of HIV infection. We assessed social network recruitment as a strategy for identifying undiagnosed cases of HIV infection.', 'In a sexually transmitted infection (STI) clinic in Lilongwe, Malawi, 3 groups of 45 "seeds" were enrolled: STI patients with newly diagnosed HIV, STI patients who were HIV-uninfected, and community controls. Seeds were asked to recruit up to 5 social "contacts" (sexual or nonsexual). Mean number of contacts recruited per group was calculated. HIV prevalence ratios (PRs) and number of contacts needed to test to identify 1 new case of HIV were compared between groups using generalized estimating equations with exchangeable correlation matrices.', 'Mean number of contacts recruited was 1.3 for HIV-infected clinic seeds, 1.8 for HIV-uninfected clinic seeds, and 2.3 for community seeds. Contacts of HIV-infected clinic seeds had a higher HIV prevalence (PR: 3.2, 95% confidence interval: 1.3 to 7.8) than contacts of community seeds, but contacts of HIV-uninfected clinic seeds did not (PR: 1.1, 95% confidence interval: 0.4 to 3.3). Results were similar when restricted to nonsexual contacts. To identify 1 new case of HIV, it was necessary to test 8 contacts of HIV-infected clinic seeds, 10 contacts of HIV-uninfected clinic seeds, and 18 contacts of community seeds.'] Are sTI patients effective recruiters of undiagnosed cases of HIV : results of a social contact recruitment study in Malawi?