Research suggests that health literacy (HL) is critical in preventing and managing health problems. However, over half of adults in Mexico report having inadequate health literacy. Research suggests the parent-child relationship can be a key predictor of developmental competencies; however, little research has examined how dyadic family interactions relate to HL. This study examined whether parent-child relationship conflict was associated with adolescent health literacy among families living in Mexico. Data from a parent-child dyads in Mexico were gathered using online surveys ( N = 746, 373 parent-child dyads). Our findings suggested that child-reported family conflict-but not parent-reported family conflict - was associated with lower adolescent health literacy. Researchers and practitioners should consider how parent-child conflict may impact adolescent health outcomes, and prioritise child reports in data collection.