ELECTROPHORESIS has been of value in determining the physico-chemical constitution of cell-free extracts of micro-organisms1,2. These studies have been confined mainly to the bacteria and no such investigation of trypanosomal extracts has been made. Moving-boundary electrophoresis has been the method most frequently employed to analyse microbial extracts although the simplicity of paper electrophoresis would be of obvious advantage. The purpose of this communication is to describe the technique for paper electrophoresis and the resultant electro-phoretic patterns of trypanosomal extracts.