The locations of cell I/O points are critical to the inter-cell flow efficiency. Traditional I/O point locating methods often focus on minimizing inter-cell flow distance. However, an inter-cell movement incurs not only inter-cell flow distance but also within-cell flow distance. I/O point locating methods that neglect within-cell flow distance will not be able to produce optimal I/O points. The negligence also causes the lack of considering the effects of within-cell facility layouts on the locations of I/O points in traditional methods. The purpose of this paper is to develop an I/O point locating method without the aforementioned shortcomings of traditional methods. (C) 1997 Elsevier Science Ltd.