Screening assays for Neisseria gonorrhoeae exhibit low positive predictive values, particularly in low-prevalence populations. A new real-time PCR assay that detects and identifies individual Neisseria spp. using melt curve analysis was compared to two previously published supplementary assays. NsppID, a 16S rRNA real-time PCR/melt curve assay developed to distinguish N. gonorrhoeae from other Neisseria spp., was compared to real-time PCR assays targeting genes reportedly specific for N. gonorrhoeae, the cppB gene and the porA pseudogene. A total of 408 clinical specimens (324 female endocervical swabs and 84 male urine or urogenital swab specimens) were screened using the COBAS Amplicor assay for Chlamydia trachomatis and N. gonorrhoeae (CT/NG) (Roche Diagnostics, Indianapolis, IN) followed by confirmatory testing via real-time PCR. The NsppID assay detected Neisseria spp. in 150/181 COBAS-positive specimens (82%), including six dual infections, and identified N. gonorrhoeae in 102 (56%) specimens. Sixty-nine of 181 (38%) specimens were positive for N. gonorrhoeae by porA pseudogene, and 115/181 (64%) were positive for cppB. However, cppB was also positive in 15% of COBAS-negative specimens, more than either NsppID (4%) or porA pseudogene (2%) assays. The porA pseudogene assay had the highest specificity for both genders but the lowest sensitivity, especially in female specimens. NsppID had a slightly lower specificity but greater sensitivity and overall accuracy. The least desirable confirmatory assay was cppB, due to poor specificity. The NsppID assay is an accurate confirmatory assay for N. gonorrhoeae detection. In addition, the NsppID assay can identify the non-N. gonorrhoeae species responsible for the majority of false-positive results from the COBAS Amplicor CT/NG assay.Neisseria gonorrhoeae is the second most prevalent sexually transmitted bacterium after Chlamydia trachomatis (4). Many N. gonorrhoeae infections are asymptomatic, especially in women, and if left untreated can develop long-term consequences, including chronic pelvic pain, pelvic inflammatory disease, and ascending infection of the fallopian tubes. Accurate diagnosis of symptomatic and asymptomatic infection is required to prevent these complications and to control the transmission of infection.Molecular assays such as the COBAS Amplicor CT/NG have high sensitivity and specificity in detecting both C. trachomatis and N. gonorrhoeae infections, and screening of high-prevalence populations results in positive predictive values (PPVs) of Ͼ80%. However, even with very specific assays, screening of low-prevalence populations lowers the positive predictive value of any test. For N. gonorrhoeae analysis of low-prevalence populations performed by the COBAS Amplicor CT/NG assay (6, 12, 32), unacceptable positive predictive values have been reported, particularly when the optical density (OD) reading is in the gray-zone of Ն0.2 to Ͻ3.5 (6). Repeat testing of the gray-zone and positive specimens has been shown to improve the specificity of the COBA...