The tsetse-fly investigation now in progress in the Northern Provinces of Nigeria is an outcome of the proposal of the Imperial Bureau of Entomology that tsetse-fly research in Africa should be put on a more organised basis. For various reasons it is not yet practicable to inaugurate this work with funds contributed by the various Colonies interested in the problem, but the suggestion so met with the whole-hearted approval of His Excellency Sir Hugh Clifford, G.C.M.G., Governor of Nigeria, and of Dr. T. E. Rice, Director of Medical Services, that it was decided to commence such an investigation at once. The helpful interest of these gentlemen has greatly aided the commencement of the work. At present the only investigators engaged are the authors of this report, the first of whom began work in July 1921 and was joined by the other in September of that year.