© 2015, International Society for Horticultural Science. All rights reserved. Mango production in northern Thailand is increasingly export oriented, as high prices ensure farmers' income. In contrast to domestic mango market, there are high quality requirements for export mango in terms of uniform shape and size. As fruit development takes place during the dry season, irrigation becomes important to improve fruit production. However, due to lacking water resources and expanding mango area, farmers are facing increasing water shortage. Therefore, deficit irrigation strategies such as partial rootzone drying (PRD) were developed to increase water use efficiency and solve the problem of fruit weight reduction during development. However, partial rootzone drying might cause drought stress response, producing proline to balance cell solution and affects fruit development. In addition, PRD might affect tree vigor and yield in the long-term. During two seasons, mango trees in a commercial orchard were irrigated by micro sprinklers, calculating application depth from evapotranspiration (ETo). Two treatments were applied: (i) full irrigation with 100% ETc; (ii) PRD irrigation with 50% ETc. Leaves were collected every week during fruit growth for proline analysis. Fruit growth and yield were recorded to determine physiological response. It was found that the differences in average proline concentration between PRD and full irrigation were not significant. However, a strong correlation was found between proline concentration and average water content. The fruit growth rates, yield and water use efficiency were similar in both treatments with a share of more than 90% marketable fruit.