Biological control is considered an important approach in the recent years for controlling many plant diseases. Trichoderma spp. is a unique genus with a wide range of activity against most important plant pathogens. In this investigation, we have evaluated antagonism of four species of Trichoderma (T. album, T. asperellum, T. hamatum and T. koningii) against root-knot nematode (Meloidogyne javanica) and Fusarium wilt disease (Fusarium oxysporum f. sp. cucumerinum) on cucumber plant at two locations (Giza and Sakha) under greenhouse conditions. Effect of Trichoderma on disease severity of F. oxysporum f. sp. cucumerinum and mortality of M. javanica (J2) were examined under laboratory conditions. Results indicate that all tested Trichderma spp. inhibited the mycelial growth of F. oxysporum f. sp. cucumerinum and gave high mortality % of M. javanica juveniles in vitro. The best antifungal activity was shown by T. album and T. hamatum against cucumber wilt pathogen.After 24 hours, T. hamatum and T. album had almost 100% nematode mortality. Under greenhouse conditions, a significant enhancement was found in growth parameters of cucumber treated with T. album and T. hamatum at two locations. The application of T. hamatum to soil infected with F. oxysporum and M. javanica resulted in the highest antagonistic effect at Giza location. All treatments caused a reduction in final population density of M. javanica whether in the presence of Fusarium or not. At Giza location, the treatment utilizing T. album were shown to be the most effective in lowering the total number of galls and egg masses on cucumber roots infected with nematodes. However, in the presence of Fusarium fungus + nematodes, T. hamatum was the best treatment. At Sakha location, no significant differences were observed among Trichoderma spp. when nematodes and fungus were used together. T. koningii with nematode only resulted in a lower number of egg masses. Most treatments were more effective in reducing M. javanica reproduction factor (RF) when the nematode was present alone. In both sites, the highest increase in chitinase activity was recorded with treatment by T. hamatum and Fusarium.