Two pot trials were conducted in Sugar Crops Research Institute, Giza Research Station, ARC, Egypt in the two successive seasons of 1992/93 and 1993/94. The purpose of this work was to assess the ef‌fect of sugar beet interference (1 sugar beef: 5 weed plants ratio) on growth characteristics of above and sub-soil parts some common asso‌dated weed species. Sugar beet exerted a noticeable reductions in height, number of branches and leaves ,fresh and dry weights of foliage and underground parts/plant of existing weed species after 105, 135 and 180 days from sowing. The extent of reductions was mainly depenent on the neighbour-ing weed species. Shoot growth reduction was more striking with bindweed (Convowulus arvensis, L.), followed by wild beet (Beta vulgaris, L.). Sugar beet interference decreased the number of branches and leaves and fresh and dry weights of aerial parts of bindweed plant than the control after 135 days from sowing by 61.4, 63.2, 78.3 and 74.7% respective‌ly. Contrarily, canarygrass (Phalaris minor Retz) can withstand competi‌tion of sugar beet without any significant reductions in its shoot growth. Other weed species: dock weed (Rumex dentatus L.); lambsquarters (Chenopodium murale L.); tooth pick (Ammi majus L.) and bermuda-grass (Cynodon dactylon (L.) Pers.) were in-between. Hazardous impact of beet interference on underground parts of weeds was more pronounced with dock weed followed by wild beet and lambsquarters, whereas tooth pick was the only non affected weed by sub-soil competition.