Contrasting results regarding elevated CO2 effects on leafdark respiration (Rd) have hampered efforts to incorporate this importantcomponent of the plant carbon budget into long-term predictions of ecologicalresponses to rising atmospheric CO2. To help resolve some of theseinconsistencies in the literature, we used meta-analysis to quantitativelysummarize 45 area-based leaf Rd (Rda) and 44 mass-based leaf Rd(Rdm) observations from independent studies on 33 species. Ouranalysis showed that across all studies, leaf Rdm was significantlyreduced (−18%, P < 0.05), while leaf Rda was marginallyincreased (+8%, P < 0.15), under elevated CO2. There weresignificant differences among categorical groups in CO2 effects onleaf Rda and Rdm. For example, leaf Rda ofherbaceous species increased 28%, but leaf Rda of woody speciesremained unchanged under elevated CO2. Plants exposed to elevatedCO2 for < 60 days had significantly higher leaf Rda atelevated compared to ambient CO2, while plants exposed to elevatedCO2 for longer period of time showed no response. The magnitude ofreduction in leaf Rdm for plants exposed to elevated CO2for > 100 days was significantly greater than that for plants exposed toelevated CO2 for < 100 days. Our meta-analysis of publishedresults suggest that the amount of carbon loss through leaf Rd will likelyincrease in a higher CO2 environment because of higher leafRda and a proportionally greater leaf biomass increase than leafRdm reduction at elevated CO2. Our results alsodemonstrated the strong dependency of Rd responses to elevated CO2onexperimental conditions.