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The purpose of this master's thesis is to study the effects of mechanical harvesting on the quality characteristics of three aromatic plants (Salvia officinalis L., Helichrysum italicum and Lavandula spp.). The comparison was carried out between a prototype lavender harvester using the stripping technique and hand-picking. The research on Salvia was conducted at the educational farm of the American Farm School (Department of aromatic and medicinal plants), while the one on Helichrysum italicum and Lavandula spp. at the fields of the producer Kampanis Antonis in Vavdos, Halkidiki. Regarding Salvia, its three most basic components were examined, a- and b-thujone and 1,8-cineole, that make up 60% of its essential oil composition. The results and diagrams show that, as far as 1,8-cineole is concerned, mechanical harvesting is superior to manual with a statistically significant difference, since it is one of the most desirable quality characteristics of Salvia. As for a- and b-thujone, hand collection appears to be better with a statistically significant difference regarding a-thujone, while for b-thujone the difference is not statistically significant. With regard to Helichrysum italicum, the main component of the essential oil is a-pinene, the content of which should be less than 25%, and it was noted that there was a significant statistical difference compared to manual harvesting where there was higher concentration of a-pinene. As for neryl acetate, the second most important main quality component of Helichrysum italicum, an increase was noted when hand-picking was used compared to mechanical harvesting. Finally, as far as Lavandula spp. is concerned, four basic quality characteristics of its oil were examined: linalool, linalyl acetate, camphor and 1,8-cineole. In all the samples examined, camphor and 1,8-cineole were not detectable and this, based on the literature, is very positive. For linalool, the difference between mechanical and manual harvesting was statistically insignificant and the detectable percentages were at very satisfactory levels. However, the percentages of linalyl acetate increased when mechanical harvesting was used and the difference was statistically significant compared to hand-picking. Taking all the results into account as well as the labor costs for the harvest of the aromatics in question, it is concluded that mechanical harvesting is more efficient as it may sometimes have a slight negative effect on the quality characteristics of oils, but it provides the producer with speed, lower costs and ease of harvesting.