This trail was carried out at Kaha Vegetable Research Station, Kalubia Egypt, during the two successive seasons of 2016 & 2017. The objective of this study was to evaluate the effect of using different bio-agents at two planting densities on damping off disease incidence of sweet pepper. Some horticultural characteristics and yield were also studied. Two planting densities i.e. planting in low density (2plants/m2) or high density (3plants/m2) were used. Six different bio-agents were used (Trichoderma viride, Bacillus subtilis and Streptomyces sp. and their mixtures, T. viride with B. subtilis, T. viride with Strptomyces sp. and B. subtilis with Strptomyces sp.). Data revealed that, low density led to decrease disease incidence and improve chlorophyll content, compared with high density. Data also show an increase in some horticultural characteristics i. e. plant height, number of leaves and branches, leaf area, fresh and dry weights per plant when low planting density was used compared with high density. Fruit quality, i.e. fruit weight, length, diameter, flesh thickness and chemical characteristics were also increased with low density. Early yield, number of fruits per plant and total yield were also increased with low density. When bio- control treatments were applied, the obtained data revealed that mixture of T. viride with B. subtilis gave the best results and the reduction percentage in disease incidence were 69.4and 66.5% during 2016 and 2017 seasons, respectively. Mixture of B. subtilis with Streptomyces sp. occupied the second rank and only 63.3 and 52.7 % reduction were recorded compare with control. When growth characteristics, fruit quality and yield were considered, the obtained data showed that the highest yield and growth characteristics were noticed when mixture of T. viride and B. subtilis was used. Integration of these two factors (planting in low plant density with mixture of bio-agents) lead to improve the efficacy of the treatment and control of the disease.