Data acquisition by Environment Canada and others over the last 20 years now allows the ยฎrst comprehensive synthesis of the riverine sediment balance of the Mackenzie Delta. The data presented here are: sediment inputs from the Mackenzie and Peel rivers at the delta head and river sediment transfers from the Upper Delta to the Outer Delta (1974ยฑ1994); in-channel and overbank sedimentation, including lakes ( post-1963); and in-channel erosion along Delta channels (1950ยฑ1981). These data indicate that the mean annual sediment input to the Delta is about 128 Mt, and the corresponding loss to oshore is about 85 Mt. The net sedimentation of 43 Mt is divided almost equally between the Upper Delta (mostly on levees and lake beds) and the Outer Delta (mostly on lake shores). Gross sedimentation within the Delta, about 50% of which is on point bars, is much higher, estimated at about 103 Mt annually: the dierence is the large amount of sediment reentrainment within the Delta, through bank erosion, primarily along Middle Channel. How much of this pointbar deposition is from settling of sediment delivered by the Mackenzie and Peel rivers (as distinct from local sediment derived from bank scour within the Delta) is not known. Such within-Delta sediment exchange (which could be as high as 50 Mt) might be important in determining the quality of sediment (nutrients, contaminants, etc) that it is being delivered oshore: it would be naรตร ve to assume that all of this sediment is from the present-day input of the Mackenzie and Peel rivers.