Based on a meta-analysis, this study aims to clarify the influence of online review valence (i.e., whether reviews in a review set are predominantly positive or negative) on various dependent variables, in particular on perceived usefulness of the reviews and on attitudes toward the product. The findings suggest that review valence affects perceived usefulness in a different way than it affects attitudes. We find an optimum impact level for perceived usefulness and a ceiling effect for attitudes. Primarily negative review sets that include few positive reviews show the strongest effect on perceived usefulness, while positive review sets that include few or no negative reviews are most successful in influencing attitudes. Additionally, review valence has a stronger influence on perceived usefulness when the reviews refer to experience (rather than search) products, and it has a stronger influence on attitudes for unfamiliar (rather than familiar) brands. Finally, the strongest influence of review valence refers to recommendation intentions. These findings provide several implications for researchers and practitioners. •The positivity degree in online reviews affects perceived usefulness differently than attitudes.•Positivity shows an optimum impact level for perceived usefulness and a ceiling effect for attitudes.•Valence effects on usefulness depend on product experience.•Valence effects on attitudes depend on brand familiarity.•The strongest influence of review valence refers to recommendation intentions.