Old-growth forests have been noted for containing significant quantities of deadwood. However, there has been no coordinated effort to quantify the deadwood component of old-growth remnants across large regions of temperate deciduous forest. We present results of a regional inventory that quantifies and examines regional and temporal trends for deadwood in upland old-growth forest remnants within Indiana, Illinois, Missouri, and Iowa. From 1992 to 1994, down wood ≥ 10 cm in diameter and standing trees ≥ 10 cm dbh were inventoried on 328 one-tenth ha plots at 12 sites. The mean ratio among the sites by diameter class of the number of standing dead to standing live trees (dead/live ratio) ranged from 0.08 to 0.11 and was consistent for trees ≤ 65 cm in diameter. The dead/live tree ratio was generally greater for old-growth than for mature second-growth forests (70 to 90 yr old). Mean volume of standing dead trees across all old-growth sites was 21.4 m³/ha and down wood was 60.4 m³/ha. However, both standing and down wood volume (total deadwood) increased along a regional gradient of increasing productivity from southwest Missouri to northeast Indiana and also increased with increasing age of dominant and codominant trees. Old-growth forests on high productivity sites averaged more pieces/ha of down wood in all diameter classes and higher volume/ha of down wood in nearly all diameter classes than did old-growth forests on low productivity sites. A chronosequence of forests from 10 yr to more than 200 yr since stand establishment indicated a sharply declining down wood volume from age 10 to 70 yr followed by increasing volume between 80 and 200 yr. For. Sci. 45(2):302-313.