Sugar beet plants were treated Two times in the field with diazinon (60%EC) and fenitrothion (50% EC) at the rate of 150 and 125 grams a. i. per 100 ml. water respectively. The first treatment was carried out when plants were five months old and repeated after 40 days.The data showed that no accumulation for diazinon and fenitrothion after 40 days from first application. Residue analysis showed that the total initial deposits determined one hour after second application were 99.05 and 28.83 ppm on and in vegetative parts of diazinon and fenitrothion treatments. These figures decreased to 0.76 and 0.05 ppm after ten days. The residue half-life values (RL50) on vegetative parts were 18 and 16 hours for diazinon and fenitrothion, respectively. No detectable amounts of diazinon and fenitrothion residues were found in the roots at all the intervals of study. This indicates that the root parts could be used safely for manufacturing sugar.