Online communities provide promising opportunities to support patient–professional negotiations that address the asymmetries characterizing health services. This study addresses the lack of in-depth understanding of these negotiations, what constitutes successful negotiation outcomes, and the potential impact of negotiation on offline health behaviors. Adopting a netnographic approach, two threads were observed from each of the four online health communities focusing on breast cancer, prostate cancer, depression, and diabetes, respectively. This analysis was supplemented with 45 in-depth interviews. The evidence suggests that online health communities can be constructed as permissible spaces. Such virtual spaces facilitate the type of patient–professional negotiations that can redress asymmetries. The critical elements of the negotiation process are identified as occupation, validation, advocacy, and recording. These support patients and professionals as they debate and resolve conflicts in how they experience health. Direct tangible offline negotiation outcomes are reported (e.g., changes in treatment plans). Implications for professional–patient partnerships are also explored.