The allergy to olive pollen is one important cause of respiratory diseases in Mediterranean countries and some areas of North America, where this tree is intensely cultivated. The presence of a great number of protein allergens in olive pollen has been reported. Eight proteins, Ole e 1 to Olé e 8, from the olive have been well characterized as inducers  of allergy. Among them, Ole e 1 is the most frequent sensitizing agent, affecting more than 70 % of the patients suffering of olive pollinosis. Some of the allergens have been recognized to have amino acid sequences or activites that correlate with known proteins : profilin (Ole e 2) Ca-binding proteins (polcalcin Ole e 3 and Ole e 8), and superoxide dismutase (Ole e 5) Other olive allergens are new proteins with no homologous counterparts in the Database blanks (Ole e 4 and Ole e 6)or with no protein function assigned (Ole e 1) . In addition to the olive tree, other pollen species, mainly from Oleaceae  family, have been found to contain protein allergens structurally or immunologically related to those olive trees. This fact allows to detect and analyze antigenic cross-reactivities involving olive allergens.