Following the first Conference in Florida, U.S.A. (1970) and the second in Krakow, Poland (1975), the Third International Conference on Ephemeroptera was held in Hinnipeg, Manitoba, Canada from the fourth to the tenth of July, 1979, at the invitation of the Inter- national Permanent Comraittee on Ephemeroptera. (H.L. Peters, U.S.A. (Chairman); I. Uu11er-Liebenau, \Jest Germany; H.J. Schoonbee, South Africa; G.F. Edmunds, Jr., U.S.A.; E.F. Riek, Australia; R. Sowa, Poland). The Conference \-laS hosted by the Freshwater Institute (Department of Fisheries and Oceans, Canada) and the University of Hanitoba and sponsored by the International Union of Biological Science. Sixty delegates from 11 countries attended. Registration for the Conference took place on July 4th, and in the evening the delegates got acquainted, or renewed old acquain- tances, at an informal gathering in the Hospitality Room at Hary Speech1y Hall, the University residence which accomodated most of the delegates. Next morning, in the Fletcher-Argue theatre, the Conference was opened by the Honorary Chairman, Dr. F.P. Ide, who welcomed the delegates, then introduced the guest speakers: G.H. Lawler, Director-General of the Hestern Region of the Canada Depart- ment of Fisheries and Oceans; P. Jarvis, Deputy Hinister, aanitoba Department of lUnes, Natural Resources and Environment, and D. R.