Today, pepper is one of the most commonly grown crops, which, apart from the soil, is increasingly grown hydroponically on inert substrates. The advantage of hydroponic cultivation is in the optimal supply of plants with water and nutrients. The use of biostimula nts reduces the effect of stress conditions on the plant and has a positiv e effect on the plant's resistance to abiotic and biotic stress factors, thus increasing the quality and yield. The research was conducted in an unheated greenhouse of the Department of Vegetable Crops at the Faculty of Agriculture in Zagreb during 2019. The aim of the study was to determine the effect of biostimulants on the yield components of treated plants relative to untreated control Four pepper hybrids (Blanchina, Menta, Vedrana and Rialto) treated with biostimulants Actiwave, Humistar and Phylgreen were tested. The experiment was set up by the split plot method in three replications. During the vegetation, the greenhouse microclimatic conditions, as well as the pH and EC values of the nutrient solution were continuously monitored. During the harvest period, the number and weight of marketable fruits, market able yield and the share of non marketable fruits were determined. Although was expected that the application of biostimulants will reduce the negative impact of stress conditions on yield componen ts, this was not fully achieved as in some cases the best results were recorded on untreated plants. Between the tested cultivars, 'Menta' with the best and 'Rialto' with the worst results stand out, with both cultivars achieving the highest yield with the use of the biostimula nt 'Actiwave'. Depending on the biostimulant treatment, from ‘Menta’ plants, between 34.2 and 52.5 marketable fruits, weighing 143 to 150 g, were harvested per m 2, resulting in a market able yield ranging from 5055 to 7490 g/m 2 ; the share of non marketable fruits ranged from 16.9 to 19.2%, with the least non marketable fruits determined on control, untreated plants.