Male couples represent a high priority group for HIV prevention interventions because primary partners have been identified as the source of one-third to two-thirds of HIV infections among men who have sex with men (MSM). HIV testing is an important component of the U.S. National AIDS Strategy. In previous research rates of HIV testing among partnered MSM have been found to be lower compared to other MSM. In this paper, we use a sample of 906 MSM recruited through internet advertisements to contrast HIV testing behavior, perceived risk of HIV infection and confidence in remaining HIV sero-negative between single MSM and MSM who report having a main partner. We also examine associations between sexual agreements and HIV testing and perceived risk among partnered MSM. Although results were marginally significant, men with a main partner had significantly higher odds of perceiving zero risk of HIV infection, higher odds of being very confident they will remain HIV-negative, and lower odds of testing for HIV in the past 6 months. Partnered men who reported they were in an open relationship had higher odds of recent HIV testing, lower odds of perceiving zero risk, and lower odds of being very confident in remaining HIV-negative, relative to those who reported monogamy. The results point to the need for dyadic interventions to tackle the underestimation of potential risk associated low HIV testing among partnered MSM. Couples HIV Testing and Counseling-CHTC-affords male couples the opportunity to learn their sero-status together and discuss the realities of their agreement and relationship and should be considered a priority intervention for male couples in the U.S.