Two plastic house experiments were conducted in 2014/2015 and 2015/2016 seasons at EL-Kassasein Research Station, Hort. Res. Inst., Agric.Res.Center, Ismailia Governorate, Egypt. It aims to study the effect of irrigation water quantities (IWQ), some bio-stimulants and their interactions on growth, plant water relationship and yield as well as water use efficiency of tomato plants under sandy soil conditions. The obtained results showed that, tomato plants which irrigated with high level of water (153 m³/plastic house) combined with Actosol + Effective microorganism (EM) as soil application, significantly increased main stem length, number of leaves/main stem, and dry weight of main stem, total and free water (%) in leaf tissues, fruit weight, yield/plant and total yield/ plastic house in both seasons. While, the lowest values of the above-mentioned parameters were recorded with the interaction between the lowest level of IWQ (91 m³/plastic house) and fertilized with the recommended mineral nitrogen dose (control) in both seasons. Bound water (%) in leaf tissues and water use efficiency as well as TSS (%) in tomato fruits were increased with the interaction between the lowest level of IWQ and Actosol + EM in both seasons.