Two field experiments were carried out in a private farm at El-Mahalla El-Kubra, Gharbia governorate during the two successive summer seasons of 2011 and 2012. The aim was to investigate the effect of nitrogen fertilization forms i.e ammonium sulphate and calcium nitrate and some bio-stimulants i.e humic acid, fulvic acid, EM and yeast extract under high temperature on vegetative growth parameters and chemical constituents in leaves of cucumber (Cucumis sativus L.) cv. Prince. The obtained results showed that the effect of N-forms was significant  on all vegetative growth parameters and chemical constituents of cucumber plants. The maximum values of these parameters were executed for the treatment of (50%NH₄ + 50%NO₃). As for foliar spraying of cucumber, plants with bio-stimulants significantly increased the mean values of the vegetative growth parameters and  chemical constituents as compared to the control treatment. The best foliar application were yeast extract at 10 g/l or effective Microorganisms (EM) at 20 ml/l. Therefore,  using nitrogen fertilization as (50% NH₄ +50% NO₃) combined with spraying yeast extract at 10 g/l or effective Microorganisms (EM) at 20 ml/l could be recommended in case of high temperature conditions.