Antiprotozoal agents (ATC code: ATC P01) is a class of pharmaceuticals used in treatment of protozoan infection. Protozoans have little in common with each other (for example, Entamoeba histolytica, a unikont eukaryotic organism, is more closely related to Homo sapiens, which belongs to the unikont phylogenetic group, than it is to Naegleria fowleri, a bikont eukaryotic organism) and so agents effective against one pathogen may not be effective against another.