Abstract: In this study we explored opportunistic endophytism of Trichoderma spp. in rice [Pusa basmati-1 (PB-1)]. Pusa basmati-1 was subjected to soil and seed treatment with five isolates. After 28 days, the root samples were assessed by microscopic analysis (light and SEM) and isolation of endophytic fungi from root samples revealed that the isolated endophytic fungus were identical to the inoculated ones. These results were further confirmed by PCR amplification of the rDNA region and tef 1 with the newly isolated Trichoderma asperellum and T. asperelloides. Consequently, the in vitro (dual culture assay) and in vivo (plant infection) studies of the antagonistic activity of the five isolates against Rhizoctonia solani showed that all isolates significantly inhibited the growth of the pathogen. In both treatments, TaR3 proved to be the best isolate. The mean horizontal spread range and relative lesion height were studied in both seed and soil treatment. In this study, it has been reported that T. asperellum and T. asperelloides is endophytic in rice upon inoculation through seed and soil treatment. This may indicate the role of T. asperellum and T. asperelloides as endophytes protecting the host against biotic stress.