Abstract: In this study, the effects of water stress at different growth stages on dynamics of flowering and fruit production of greenhouse grown pepper plants were investigated. Irrigation treatments included complete restoration of water use during the whole growing season (control), water deficit during the vegetative phase (vegetative stressed stage) and water deficit during the reproductive phase (reproductive stressed stage). Soil water content was periodically measured; leaf water and osmotic potential, net assimilation rate, stomatal conductance, transpiration rate, intercellular CO2 concentration were also measured on pepper leaves. Flowers were monitored till the end of the crop cycle to calculate fruit setting. Leaf water and osmotic potential changed with time according to the soil water content of stressed treatments. Photosynthesis was lower in vegetative stressed stage and reproductive stressed stage treatments during the water stress periods compared to the well watered control. During the vegetative phase, water stress significantly reduced the number of flowers per plant, decreasing from 30.9 to 10.7 in the control and vegetative stressed stage treatments, respectively. Unlike flowering, setting was not affected by water stress, when it was imposed during both the vegetative and reproductive phases. Total pepper yield gradually decreased going from the fully irrigated treatment to the treatment stressed during the vegetative phase, getting to the lowest value in the treatment stressed during the reproductive phase (5644, 2040 and 875 g m-2, respectively). Since setting was not affected by water stress, the attention on irrigation scheduling should not be paid only on reproductive phase, but on the whole growing cycle.