Seed fall was measured for 11 years in a 200-year-old stand of sugar maple (Acer saccharurn Marsh.), yellow birch (Betula alleghaniensis Britton), and beech (Fagus grandifolia Ehrh.) in New Hampshire. These species accounted for 98 percent of the seed fall. Yellow birch had 5 good seed years, sugar maple had 3, and beech had none. Time of seed fall varied among species and years. Viable seed fall of yellow birch in good seed years began in August and continued through autumn and winter. Most of the viable sugar maple seed fell during a short period in October, just before and after leaf fall. Beech seed fall was similar, but occurred slightly later than sugar maple. Seed losses caused by pollination or fertilization failure, abortion, incomplete development, insects, small mammals, and birds varied widely among years, but averaged about 2/3 of the potential seed crop. Losses often were proportionally greater during poor seed years.