Bypassing the photorespiratory pathway is regarded as a way to increase carbon assimilation and, correspondingly, biomass production in C 3 crops. Here, the benefits of three published photorespiratory bypass strategies are systemically explored using a systems-modeling approach. Our analysis shows that full decarboxylation of glycolate during photorespiration would decrease photosynthesis, because a large amount of the released CO 2 escapes back to the atmosphere. Furthermore, we show that photosynthesis can be enhanced by lowering the energy demands of photorespiration and by relocating photorespiratory CO 2 release into the chloroplasts. The conductance of the chloroplast membranes to CO 2 is a key feature determining the benefit of the relocation of photorespiratory CO 2 release. Although our results indicate that the benefit of photorespiratory bypasses can be improved by increasing sedoheptulose bisphosphatase activity and/or increasing the flux through the bypass, the effectiveness of such approaches depends on the complex regulation between photorespiration and other metabolic pathways.