Dual treatments of compost and Trichoderma spp. to control damping-off and root rot diseases of lentil were investigated.The obtained results showed that T. harzianum and T. viride were suppressive against lentil pathogen (R. solani). Likewise, both types of compost showed suppression on pathogen at 50%. The microbial population in the two composts was determined, where Com 2 showed the higher population of the recovered microbial load than Com1. Under greenhouse and field conditions, application of Trichoderma spp. and both composts individually or in combination significantly reduced the percentage of damping-off and root rot diseases of lentil caused by R. solani and increased plant survival rate of lentil compared to the infected control. It has been observed that a combined inoculation of Trichoderma spp. and both types of compost significantly increased the plant height, number of nodules and crop parameters, i.e., number of pods, number of seeds, weight of seeds as well as protein content.