The purpose of diploma thesis was to show a favourable effect of regular water supply on yield of pear (Pyrus communis L.) cultivar 'Williams'. We evaluated the effect of drip irrigation and irrigation with micro-sprinklers on the quantity and quality of pear cultivar 'Williams'. The experiment was carried out in pear orchard at Bistrica ob Sotli in 2015. We measured the indicators of vegetative growth and generative development. Irrigation had a positive effect on the fruit development of cultivar 'Williams', since the fruit of irrigated trees had larger fruit dimensions. Trees with drip irrigation had the largest fruit number/tree and the highest yield/tree. Furthermore, trees with drip irrigation had the lowest flesh firmness and titratable acids content, but the differences between the treatments were not significant. Trees with micro-sprinkler irrigation had the highest yield coefficient, the fruit had higher soluble solids content and titratable acids content compared to control. The fruits of the trees, which were irrigated with micro-sprinklers, were less firm compared to control fruit.