The aim of this study was to evaluate the effect of different irrigation systems on cv. Cobrançosa olive oil main components, in a semiarid region in the Northeast of Portugal (Alfândega da Fé, 2019) - regulated (RDI) and sustained deficit (SDI) against well-irrigated controls (FI). Total polyphenols (Folin) were higher in RDI than SDI and FW treatments. Among the phenolic components, hydroxytyrosol and tyrosol derivatives (HPLC, after acid hydrolysis), were higher in olive oils obtained under SDI, potentially complying with the nutrition allegation allowed in Regulation (EU) No 432/2012, (“polyphenols in olive oil contribute to the protection of blood lipids against undesirable oxidation”), while the amounts in FW and RDI olive oils were 10% lower to the threshold. Olive oil vitamin E (mainly α-tocopherol) was also higher in oils obtained from SDI deficit irrigation treatments while oils from RDI had values very close to FI treatments. Olive oil bitterness, evaluated by K225, was highly positively correlated with TP (r2 = 0.94, p<0.01). The fatty acidy profile was not affect by the irrigation regime. Results are preliminary and need to be continued to extract solid conclusions.