Human leukocytes retract pseudopods in response to physiological fluid shear, a phenomenon that serves to keep circulating leukocytes in a spherical state. We show here that leukocyte fluid shear response is attenuated irreversibly by centrifugation. Inhibition of shear response depends on duration and magnitude of acceleration during centrifugation and time duration after centrifugation. Even after low-speed centrifugation, leukocytes no longer retract pseudopods during shear application. After centrifugation at higher acceleration, leukocytes project pseudopods instead of retracting during shear application, which can be suppressed by a calcium channel blocker. We examined the role of fluid shear response in vivo by reintroduction of centrifuged cells into the rat circulation. Centrifuged leukocytes have a significantly enhanced tendency to migrate into tissue. These observations indicate that centrifugation may irreversibly damage the fluid shear response of leukocytes. It causes an impaired leukocyte behavior after reintroduction into the circulation, suggesting that shear response is a requirement for normal passage of leukocytes through the microcirculation.