Interactive damage effects of stand loss and plumule abscision from seedcorn maggot,Hylemya platura(Meigen), on ‘Amsoy 71’ soybean growth and yield were investigated by using actualand simulated-damage methods. Stand reduction affected seed yield more than the presence of surviving seedlings wihtout plumules. Over all years, seed yields were greatest at 29.7 plants per 1-m row. At all plant stands, the seedlings without plumules were shorter and produced less leaf area, fewer flowers, and fewer pods than did normal plants. This retarded growth reduced leaf area index, flowers per unit area, and pods per unit area. The decrease in pods per unit area was accompanied by an increase in beans per pod. When some of the surviving seedlings lacked plumules, seed yields were reduced at poor plant stands in some years. Plant-growth characteristics were very similar for actual and simulated damage. Seed yield comparisons between actual and simulated damage suggested that seedcorn maggot injury to cotyledons had a small, negative effect on seed yield