The aim of the study was to access the anti-bacterial and anti-fungal activity on the growth of Alternaria porri under in vitro condition. The antagonistic activity of bacterial and fungal antagonists (Pseudomonas and Trichoderma spp.) was determined by the dual culture technique both on King’s B and PDA media respectively, Paper disc assay and Agar well mathod. Plates were incubated at 28ºC for 7 days and 2 days. The antagonistic activity of these antagonists was evaluated by mycelial growth and mycelial dry weight of test fungus (Alternaria porri). | Antagonistic potential of native isolates of Trichoderma longibrachiatum and pseudomonas fluorescens against Alternaria porri Ellis Cif.