Flow cytometry (FCM) is a powerful tool that allows analysis of thousand of cells in a few seconds,at the single cell level. In the last 15 years, researchers have used FCM to investigate the cellularmachinery of invertebrates. Analyses have focused on functions linked to innate immunity, such asphagocytosis and natural killer cell activity, as well as on the sensitivity of invertebrate cells to aparticular stress or to a toxic agent. Further, FCM has been employed to recognize antigens, or atleast immunodominant epitopes, shared in common with mammalian cells, including humanleukocytes. In this review, main studies that have utilized FCM to investigate either phenotype andfunctions of invertebrate cells are reported and discussed
