Although different nanosized materials, including quantum dots (QDs), are intended to be used for biomedical applications, their interactions with microvessels and their inflammatory potential are largely unknown. In this in vivo study we report that leukocyte recruitment is modulated in the presence of quantum dots. We found that the surface chemistry of QDs strongly affects their localization in postcapillary venules, their uptake by perivascular macrophages, and their potential to modify steps of leukocyte recruitment.