Regulated deficit irrigation (RDI) is the strategy of reducing irrigation rates during a specific period of growth and development, with the objective of conserving water and managing plant growth while maintaining or improving yield and fruit quality. Mature tart cherry (Prunus cerasus L. 'Montmorency') trees in a commercial orchard were subjected to a range of irrigation deficits from pit hardening to harvest during the 2007 and 2008 seasons. Irrigation treatments replaced from 62% to 96% of ETc, during that period. Midday stem water potential measurements were significantly different among treatments before harvest. However, fresh weight yield at harvest did not differ significantly among irrigation treatments in either year (P-value=0.64). In 2008 the amount of undersized fruit eliminated during packout was significantly higher in the treatments replacing 61% and 68% of ETc than in the control (P-value<0.0001), but only amounted to 2.0% and 1.4% of total yields, respectively. This small increase in undersized fruit did not significantly affect packout. Fruit quality measurements, such as soluble solids concentration and chroma of whole intact fruit, increased with the severity of the irrigation deficit. Visible surface bark damage from mechanical harvesting appeared less severe as deficit levels increased. Return bloom was not significantly affected by irrigation treatments.