Cyanobacteria (blue-green algae) produce many metabolites that are directed towards competing photoautotrophs. Such algicidal compounds might offer new approaches for the selective inhibition of the malaria parasite, Plasmodium falciparum, as this organism contains an organelle (apicoplast) of algal origin [1]. In this communication, we report the identification of two classes of cyanobacterial secondary metabolites with antiplasmodial activity. Aerucyclamides A-D [2] are heterocyclic peptides that are ribosomally produced [3] by Microcystis aeruginosa PCC7806. Nostocarboline is a chlorinated N-methylated carbolinium alkaloid from Nostoc 78-12A [4]. Both compounds display submicromolar IC50 values against Plasmodium falciparum, with a pronounced selectivity towards rat myoblasts. Their respective potential ecological roles and therapeutic potentials will be discussed.