This study was conducted in 2007-2008 to determine the effects of different irrigation regimes on yield, quality and water-yield relationships of young dwarf 'Gala, Galaxy' apple trees in Isparta-Turkey. Irrigation water was applied based on a ratio of class A pan evaporation (rates of 0.0 (k(cp)0), 0.25 (k(cp)1), 0.50 (k(cp)2), 0.75 c (k(cp)3), 1.00 (k(cp)4) and 1.25 (k(cp)5)) with 5-day intervals. The effects of irrigation regimes on yield and fruit weight were statistically significant. Seasonal evapotranspiration was measured as 246.5-608.2 mm and 289.3-631.9 mm in 2007 and 2008, respectively. Water use efficiency lead to a yield ranging from 0.0023 to 0.0055 t ha(-1)mm(-1) and from 0.0033 to 0.0111 t ha(-1)mm(-1) and irrigation water use efficiency varies from 0.0009 to 0.0073 t ha(-1)mm(-1) and from 0.0045 to 0.0186 t ha(-1)mm(-1) in 2007 and 2008, respectively. The annual average yield response factor, ky, was 1.22. As a result of the research, it was concluded that the irrigation schedule for the 0.75 k(cp)3 treatment, applying 0.75 of evaporation from class A pan, could be used in the irrigation of young dwarf apple trees without evident reduction in yield and that high water use efficiencies could be obtained.