This volume of Advances in Parasitology has a predominantly protozoological flavor. - The questionable pathogenicity of Blastocytis, a ptorist closely related to amoeboflagellates - Discussion of Giardia and the evidence of early branching of the eukaryotic stem - Full overview of current knowledge of the immunology of Leishmania - Explanation of the way trypanosomatids transport nutrients and ions across their membranes - A review of the biology of the coccidian parasites of fish with extensive illustrations - A review of the sexuality of parasitic crustaceans