Results of 5 years of research into super-high- density olive (Olea europaea L.) growing are presented in this paper. One-year-old olive trees of cultivars 'Arbequina IRTA-i18®', 'Arbosana-i43®', 'Koroneiki-i38®', 'Sikitita®' and 'Tosca 07®' imported from Spain (Todolivo) were planted in a trial orchard in Katel tafilić, near Split, in April 2011. Planting distances were as follows: 3.7×1.35, 3.7×1.55 and 3.7×1.75 m. Trees were trained as spindles. Trees were micro-irrigated in the first 4 years after planting. Vigour, aptitude of individual cultivars for training-form formation, suckering, ripening time, annual yield per tree, cumulative yield (2012-2015), average fruit weight, fruit dry matter (%), oil percentage and oil quality obtained by micro- processing in 2015 were analysed. Cultivars differed significantly in the biological and pomological characteristics recorded. 'Arbosana' and 'Koroneiki' ripened late, after harvest and processing of commercial Croatian cultivars. 'Koroneiki' had the highest cumulative fruit yield as well as fruit dry matter percentage. Oils of all cultivars belonged to the extra virgin olive oil category, from very mild and sweet 'Sikitita' oil suitable for first-time olive oil consumers to the very astringent oil of 'Koroneiki'.