Abstract. An evaluation of three new rapid diagnostic test kits for human immunodeficiency virus types 1 and 2 (HIV-1/2), hepatitis B surface antigen (HBsAg), and syphilis involved a two-phase comparison of rapid diagnostic assays using prospectively collected from hospitals and clinics in Ho Chi Minh City, Vietnam. After specificity and sensitivity testing, three new rapid diagnostic test kits were tested in parallel with six commonly used diagnostic test kits. The Determine HIV-1/2 test had fewer indeterminate or equivocal results than the Capillus HIV-1/HIV-2 or HIV Blot 2.2 tests. However, the Determine HIV-1/2 test yielded one false-positive result when compared with the Serodia HIV, HIV Blot 2.2, and microparticle enzyme immunoassay (IMx) HIV tests. The Serodia HBsAg test yielded more false-negative results when compared with the Determine HBsAg diagnostic test kit. The results of the syphilis diagnostic tests evaluated in this clinical trial consistently agreed with those of the rapid plasma reagin test for syphilis. The Determine Syphilis Treponema pallidum (TP) test had three false-positive results compared with the Serodia TP and the Serodia TP•particle agglutination (PA) tests, which had two false-positive results that were confirmed as negative by an ELISA. Application of these serologic tests within this comparative evaluation framework, using the World Health Organization alternative testing strategies, proved to be an effective way to determine serostatus related to HIV, hepatitis B, and syphilis.In many developing areas worldwide, field and clinic laboratory capabilities may be insufficient for the detection of infectious agents for definitive clinical diagnostic purposes. The absence of simple, rapid diagnostic testing methods for sexually transmitted diseases (STDs) and hepatitis has significantly hampered public health efforts to retard the spread of these diseases. The inability to provide tests for quick recognition of human immunodeficiency virus (HIV), hepatitis B, and syphilis has allowed infected individuals to unknowingly spread the disease through sexual contacts, blood donations, and intravenous needle sharing. In cities throughout Asia, current laboratory evaluation of blood specimens may preclude case follow-up and counseling due to a long time lag between initial sample collection and conventional test completion. High-risk populations typically seek treatment during clinic visits in association with acute episodes and are not likely to return a second time for test results.Diagnostic technology is adapting itself for application in developing countries. Advancements in the laboratory diagnosis of HIV/acquired immunodeficiency syndrome (AIDS), hepatitis B, and syphilis have considered the following conditions, including: 1) speed of results; 2) test validity and accuracy; 3) minimal specimen requirement; 4) variable type of specimen, including whole blood; 5) ease of test kit use, with few requirements for specialized laboratory equipment; and 6) stable reagents, requiring no refri...