A study was carried out to test the antagonistic potential of four isolates of Trichoderma viride and eight isolates of T. harzianum and five isolates of T. reesei against F. oxysporum f. sp. dianthi, the cause of Fusarium wilt in carnation. T. harzianum (Th2) showed the maximum inhibition of mycelial growth of F. oxysporum f. sp. dianthi. (45.33%) over control followed by T. harzianum (Th6) and T. viride (Tv3) with 42.11 and 38.66 per cent inhibition respectively. The Competitive Saprophytic Ability (CSA) and colonization by each isolates of Trichoderma spp. was assessed. Among the 17 isolates, Th2 registered 61.84 per cent colonization followed by Th6 with 59.12 percent colonization. All other isolates of Trichoderma spp. were inferior to Th2 in its saprophytic ability. The antagonistic isolates of Trichoderma spp. were also tested for production of antifungal volatiles and their effect on the growth of F. oxysporum f. sp. dianthi. All the isolates were found to produce volatile metabolites, which inhibited the mycelial growth of test pathogen at varing levels from 16.33 to 50.11 percent.