Ong JJ, et al. - As men who have sex with men (MSM) are at high risk of human immunodeficiency virus (HIV)/syphilis, researchers describe patterns of HIV/syphilis testing, and examine factors associated with never testing for HIV/syphilis in China to inform strategies for dual testing. Findings revealed 35% had never tested for human immunodeficiency virus/syphilis, and among human immunodeficiency virus testers, only 51% had ever tested for syphilis. Relative to men who had ever tested for both infections, those with increased probability of never testing for HIV/syphilis include non-gay sexual identity, not disclosed their sexuality/sexual history with men other than their regular partner or with health professionals, no condomless sex with casual partners in the last 3 months, no community engagement in sexual health, and mainly met partners offline.