The resistance of malaria parasites to current anti-malarial drugs is an issue of major concern globally. Recently we identified a Plasmodium falciparum cell membrane aspartyl protease, which binds to erythrocyte band 3, and is involved in merozoite invasion. Here we report the complete primary structure of P. falciparum signal peptide peptidase (PfSPP), and demonstrate that it is essential for parasite invasion and growth in human erythrocytes. Gene silencing suggests that PfSPP may be essential for parasite survival in human erythrocytes. Remarkably. mammalian signal peptide peptidase inhibitors (Z-LL)(2)-ketone and L-685,458 effectively inhibited malaria parasite invasion as well as growth in human erythrocytes. In contrast, DAPT, an inhibitor of a related gamma-secretase/presenilin-1, was ineffective. Thus, SPIR inhibitors specific for PfSPP may function as potent anti-malarial drugs against the blood stage malaria. (C) 2009 Elsevier Inc. All rights reserved.