The aim of the experiment was to study the effects of foliar boron (B) application on nutrient uptake and fruit quality of tart cherry (Prunus cerasus L.). The examination was conducted during 2008-2009 on four mature popular Hungarian tart cherry cultivars 'Oblacsinszka', 'Érdi botermo', 'Újfehértói fürtös' and 'Petri' grown in Eastern Hungary on an acidic sandy soil with low B content. Trees were treated with B by foliar application (0.5% B). Foliar treatments were made in the spring at full bloom. Trees untreated with B served as a control. B sprays had no consistent effect on summer leaf B status, increasing leaf B in only two cultivars ('Oblacsinszka', 'Újfehértói fürtös'). Moreover, leaf B content was strongly influenced by cultivar. Also, treatments had inconsistent effects on internal fruit composition. Monosaccharides, vitamin C and organic acid contents of sour cherry were more strongly affected by cultivars than applied treatments.