This study was carried out during 2009 and 2010 years for determining the effects of different irrigation water levels on the fruit yield and quality parameters and the water-yield functions of 'Jersey Mac' apple variety grafted on M9 rootstock. Irrigation treatments were control (CI) and deficit irrigations in which 75% (DI-0.75), 50% (DI-0.50) and 25% (DI-0.25) of the irrigation water applied to the Cl. All treatments were irrigated twice weekly by drip irrigation method. The irrigation water amount applied to the treatments varied between 107.6 (DI-0.25) and 437.4 mm (CI). The highest and the lowest seasonal evapotranspiration values were determined as 532.6 mm in CI and 245.7 mm in DI-0.25, respectively. The effects of different irrigation levels on yield were significant (p<0.01). Whereas the highest yield was obtained in CI, this was followed by DI-0.75 and DI-0.50 and the lowest yield was obtained in DI-0.25. The highest water use efficiency (WUE) and irrigation water use efficiency (IWUE) were 3.76 and 8.20 kg m(-3) in DI-0.50 and DI-0.25, respectively. The average yield response factor (ky) value for both years was 0.89. This study concluded that DI-0.50 with high water use efficiency and acceptable yield and quality loss under limited water conditions could be used for the irrigation of dwarf apple trees. However, it can be stated that CI treatment, the plant water requirement is fully met, will be more appropriate under conditions where higher yield is aimed and the water is sufficient.