The black cutworm Agrotis ipsilon, is a polyphagous pest which is often difficult to be controlled due to its feeding behavior and hidden life style of the larvae. Many microorganisms live in soil such as entomopathogenic fungi and nematodes can be used as natural biocontrol agents against A. ipsilon larvae. The present study illustrated the efficacy of the entomopathogenic fungi (EPF), Beauveria bassiana and Metarhizium anisopliae and the entomopathogenic nematodes (EPNs), Steinernema carpocapsae and Heterorhabditis bacteriophora for A. ipsilon 4^th instar larvae control. It was found that B. bassiana was more virulent than M. anisopliae with LC₅₀: 74.419x 10² conidia/ml while M. anisopliae LC50 value was 171.963x 10² conidia/ml. Also, S. carpocapsae was highly virulent to A. ipsilon 4^th instar with LC₅₀ value: 25.277 IJs/cm² then H. bacteriophora with LC₅₀: 38.534 IJs/ cm². The interaction (synergy, additivity or antagonism) between EPF and EPNs were assessed in order to make a decision of suitable treatments and application times of both agents in the field to derive maximum benefit from them. B. bassiana was compatible with both tested nematodes either applied simultaneously or when application the tested nematodes was delayed. M. anisopliae showed antagonistic interactions when simultaneously combined with both tested nematodes. The synergistic levels were observed with 72hs delayed application of both tested nematodes.