Objective: We evaluated the performance characteristics of APTIMA Trichomonas vaginalis (ATV) transcription-mediated amplification (TMA) for diagnosis of T vaginalis (TV) infection from female vaginal swab, endocervical swab, and urine specimens and from male urethral swab and urine specimens. Performance of ATV TMA was compared with wet mount microscopy, culture, and polymerase chain reaction (PCR). Study Design: In all, 296 female and 298 male subjects who attended the Jefferson County Health Department sexually transmitted diseases clinic were enrolled in the study and provided specimens for each test. Results were analyzed using 3 interpretative algorithms. Results: For women, vaginal swab ATV TMA was significantly more sensitive than wet mount or culture. In male subjects, urethral swab ATV TMA was significantly more sensitive than culture or PCR. Conclusion: ATV TMA provides a sensitive, commercially available nucleic acid amplification test for improved diagnosis of TV in male and female patients. © 2009 Mosby, Inc. All rights reserved.