After using 5 aphicides in 1995-96 and studying their ability to control tobacco aphids, 3 better chemicals were chosen and compared as below. In 1997 three aphicides: Imidacloprid 200 sl 300 ml/ha, pirimicarb 50% DG 500 g/ha and pymetrozin 25% wp 1 kg/ha were used and compared in a large scale design. The results showed that: 1 - During the first 5 days after treatment (DAT), the 3 chemicals had an efficacy of above 95%. 2 - At 7 DAT the control level of pirimicarb decreased to less than 80%. 3 - At 15 DAT the efficacy of pirimicarb fell to less than 20% whereas the two others kept their ability up to above 80%. 4 - At 21 DAT the efficacy of chemicals was: pirimicarb no efficacy (same as untreated control), pymetrozin 50% and imidacloprid 60%. 5 - Overall, the duration of the efficacy of Imidacloprid and pymetrozin was much longer than for pirimicarb. 6 - None of the chemicals showed phytotoxicity on tobacco. 7 - It seems that the efficacy of Imidacloprid and pymetrozin on red aphids is higher than that of pirimicarb, in comparison with green aphids.