The bioassay experiments were conducted at the Faculty of Agriculture, Tanta University, to de-termine the sensitivity of various plant seedlings to the inhibitory effects on their growth caused by several herbicides, namely atrazine, metribuzin, pendimethalin, and linuron. The plant species used included oat, wheat, barley, soybean, cucumber, and mallow (molokhia). The primary aim was to identify the most sensitive plant species for estimating residue levels of these herbicides in agricultural environments, utilizing an economical and cost-effective approach. The results revealed a positive correlation between herbicide concentrations and their biological effects on the seedlings of all the studied plant species. Sensitivity to the toxic effects of these herbicides was demonstrated at levels lower than one part per million for all plant species. Oat was the most sensitive plant to the toxic effects of atrazine and metribuzin, while wheat exhibited the highest sensitivity to pendimethalin. In contrast, mallow (molokhia) and cucumber exhibited statistically similar sensitivity to linuron. In conclusion, the seedlings of these plant species can be effectively employed for monitoring residual herbicides in agricultural environments in an economical, straightforward, and highly accurate manner within the range of parts per million