Background: Serotonin (5-HT) contributes to the pathogenesis of chronic inflammatory diseases known to have defects in apoptotic cell removal (i.e. efferocytosis). Results: 5-HT impairs macrophage efferocytosis via 5-HT transporter-dependent activation of the RhoA/Rho kinase pathway. Conclusion: Results show a novel mechanism by which 5-HT might disrupt resolution of inflammation. Significance: Targeting the 5-HT transporter may have a therapeutic role in chronic inflammatory disorders.© 2014 by The American Society for Biochemistry and Molecular Biology, Inc. Published in the U.S.A.