This paper assesses how knowledge of HIV status gained through HIV testing and counseling (HTC) by married individuals affects divorce, the number of sexual partners and the use of condoms within marriage. Instrumental variable probit and linear models are estimated, using a randomized experiment administered as part of the Malawi Longitudinal Study of Families and Health. The results indicate that knowledge of HIV status (1) does not affect chances of divorce for either HIV-negative or HIV-positive respondents; (2) reduces the number of sexual partners among HIV-positive respondents, and (3) increases condom use with spouses for both HIV-negative and HIV-positive respondents. These results imply that individuals actively respond to learning HIV status through HTC, invoking protective behavior against future risk of HIV/AIDS for themselves and their actual and potential sexual partners.