This study investigated the effects of different drip irrigation programs on boll number, shedding percentage, and yield of cotton. The amount of water used was based on free surface evaporation from a screened class-A pan. Irrigation treatments consisted of two different irrigation intervals (I1:5 days; 12: 10 days), three plant-pan coefficients (K(cp)1: 0.75; K(cp)2: 0.90; K(cp)3: 1.05) and two different wetting factors (P1: 0.70 (constant) and P2: based on cover percentage of the crop). The first irrigation was carried out when the available water in the 120 cm of the soil profile was at the 40% level.