The objectives of the present study were to investigate the degradation of lignocellulosic complex of corn straw (CS) by the treatment with Pleurotus ostreatus (PO), Pleurotus eryngii (PE) and Lentinula edodes (LE) and to determine both the most effective fungus and incubation time. The chopped corn straws were treated with PO, PE and LE, and incubated for 10, 20, 30 and 40 days at 26 0 C. Chemical composition of control (CS-C) and treated corn straw (CS-PO, CS-PE and CS-LE) samples were determined. The in vitro true digestibilities of dry matter (IVTDMD), neutral detergent fiber (IVTNDFD), acid detergent fiber (IVTADFD) and acid detergent lignin (IVTADLD) of CS-C, CS-PO, CS-PE and CS-LE were determined by Ankom Daisy II incubator. PO treatment at 30 days incubation of corn straw increased the in vitro true digestibility by approximately 17%. The obtained results showed that the most effective fungus was Pleurotus ostreatus and incubation time was 30 days.