The most important biotic stress factor impacting tomato crop biophysical, biochemical, physiological, and morphological features is water stress. A field experiment was conducted to investigate the effect of water stress at different growth stage on yield and water productivity and to identify the most sensitive growth stage to deficit irrigation. The study was conducted for three non-consecutive years at Mekhoni Agricultural Research Center, Raya valley, Ethiopia. The experimental treatments were four crops growing stages (initial, development, mid and maturation stages) and three deficit irrigation levels (85% ETc, 70 % ETc and 55% ETc levels) and control irrigation of 100% ETc. The design of the experiment was split plot design with three replications.