Essential oils were obtained from four selected aromatic plants namely: clove, fennel, rosemary and thyme. Their contents of total polyphenols were determined. The antioxidant activities of the studied aromatic plant oils on sunflower oil comparing with the synthetic antioxidant Butylated Hydroxy Toluene (BHT) were determined by a Rancimat apparatus. Antioxidative effect of the extracted aromatic plant oils on the oxidative stability of sunflower oil during heating up to 18 hours was also evaluated. The obtained results indicated that, the studied aromatic plants were rich in phenolic contents which ranged from 9.32 to 19.82 mg as gallic acid/100g on dry weight base. The highest level of total phenolics was found in rosemary followed by fennel and clove, while thyme recorded the lowest. The induction periods determined by Rancimat for sunflower oil treated by 200 ppm of (BHT) or 400 ppm of extracted aromatic plant oils were greater than that of control with more efficiency by using the aromatic oils. Beside, addition of aromatic plant oils to sunflower oil minimized peroxidation and increased its oxidative stability during hating up to 18 hours.