The effects of four densities of annual broadleaf weeds and annual grass weeds and an equal combination of the two on the yields of sugar beet (Beta vulgaris L.) roots and tops, percent sucrose and total solids, average diameter of beet roots, and total plot yields were studied during 1964 and 1965. Broadleaf weeds were more competitive than annual grass weeds and the effects of an equal combination were intermediate. Without cultivation, all weed densities reduced the yield of beet roots below the weed-free plots. Twenty broadleaf weeds/sq ft were required to reduce yields when plots were cultivated and weeds were limited to a 10-in band over the beet row. The effects on the yield of beet tops, average root diameter, and total plot yield were similar to the effects on beet root yield. The components of total plot yield are examined. No weed density had a real effect on beet stand, percent total solids, or percent sucrose of the beet roots.