The existence of Tomato yellow leaf curl virus (TYLCV) was figured out in different locations in Al-Ahsaa of Saudi Arabia. Polymerase chain reaction (PCR) results of samples collected showed that TYLCV existed in all locations. Using AVcore and ACcore primers, begomoviruses family were detected in symptomatic tomato plants and by using TYv2664 and TYc138 (specific primers for the detection of TYLCV), the results proved that the samples were infected with TYLCV. The lipid-soluble fraction of healthy and infected tomato leaves extract was compared using gas chromatography techniques. A total of 46 compounds were identified in both healthy and virus-infected leaf tissues; among which 37 metabolites were common between both samples and increased or decreased in concentration due to the virus attack. Nevertheless, eight compounds were exclusively detected in the infected samples with only one compound consumed and thus recognized only in the healthy samples. The classifications and roles of the identified metabolites were discussed from the point of view of plant defense mechanisms or virus resistance against plant defense. Key words: Tomato yellow leaf curl virus (TYLCV), begomoviruses, Polymerase chain reaction (PCR), gas chromatography.