In this study, I examined how HIV-negative gay men in serodiscordant relationships constructed HIV-negativity and serodiscordance online through their use of language. Using Potter and Wetherell’s (1987) discursive psychological approach, I analyzed 22 online postings, focusing on the linguistic resources HIV-negative partners drew on to talk about serodiscordance and their own HIV-subjectivities, respectively. Based on my analysis of the material, participants organized their talk around two central interpretative repertoires. Specifically, they described their serodiscordant relationship (a) as a form of alliance, and (b) as a site of tensions. I discuss the findings in relation to the existing literature on the topic of serodiscordance among gay couples, and I comment on the limitations of the study, recommendations for researchers, as well as implications for counselling practitioners.