Despite their huge variety, all fungal terpen are synthesized from few precursors by terpene synthase (TSs) enzymes. Isopentenyl-pyrophosphate and its isomer dimethyl-allyl pyrophosphate, both synthetized from acetyl-CoA, are the five carbon (C) isoprene building blocks for the biosynthesis of linear polyprenyl pyrophosphates: C10 geranyl pyrophosphate (GPP), C15 farnesyl pyrophosphate (FPP) and C20 geranylgeranyl pyrophosphate (GGPP) [17]. These molecules are synthesized by the isoprenyl pyrophosphate synthases (IPSs) and constitute the precursors that undergo further modifications by terpene cyclases (TCs) and preanyl transferases (PTs), the core enzymes mediating the committed steps in terpenoid biosynthesis [18]. According to the origin of their scaffolds, terpen can be distinguished in those exclusively formed by isoprenyl units (C10 monoterpenes, C15 sesquiterpenes, C20 diterpenes, C25 esterterpenes and C30 triterpenes), and those of mixed origin (meroterpenoids, indole terpenoids and indole alkaloids). Although many terpenes have been isolated from _Trichoderma_ species, there is no extensive information about TS genes involved in their biosynthesis, and only a few members of the TS family have been experimentally characterized [19]. Functional characterization of TS genes in _Trichoderma_ has been mainly focused on the trichodiene synthase (TRIS)-encoding gene, which catalyzes the first committed step in the biosynthesis of trichothecenes harzianum A and trichodermin in _T. arundinaceum_ and _T. brevicompactum_, respectively [20; 21; 22; 23; 24; 25]. Other _Trichoderma_ TS genes experimentally characterized are _erg-20_ of _T. reesei_, encoding a farnesyl pyrophosphate synthase [26], and _vir4_, required for the biosynthesis of mono- and sesquiterpenes in _T. virens_[27]. Furthermore, genome mining studies have assessed the complete TS-gene family in _Trichoderma_, however, in those cases, the diversity of the genus has been mainly limited to three species--_T. virens, T. atroviride_ and _T. reesei_[19], or the study has been merely quantitative [28; 29; 30]. Given the scarce information available about the diversity within the TS-gene family in _Trichoderma_, the first part of this work was focused on the genomic characterization of the whole TS arsenal of 21 strains belonging to 17 _Trichoderma_ spp., thus covering a wide number of species with different lifestyles. This provides the most extensive overview of the terpenoid biosynthetic potential of the genus and reports the distribution of each class of TSs across the species. In addition, aimed at shedding some light on the environmental signals regulating the TS genes in _Trichoderma_, in the second part of the work we assessed the expression patterns of nine TSs in different conditions associated to the ecology of these fungi, using _T. gamsii_ T6085 as a model. During the past 10 years, _T. gamsii_ T6085 has been evaluated as BCA against _Fusarium graminearum_, the most aggressive causal agent of Fusarium Head Blight (FHB) on wheat. T6085 is able to reduce the growth of the pathogen as well as the production of deoxynivalenol (DON) [31; 32], growing in the presence of high DON concentrations (50 ppm) and reducing FHB symptoms and the development of _F. graminearum_ peritechia on wheat straw [33; 34; 35; 36]. In addition, the fungus establishes a beneficial interaction with wheat roots, behaving as an endophyte and inducing the plant defense responses [36]. The versatile lifestyle of _T. gamsii_ T6085 enabled us to investigate the TSs expression patterns in artificial media simulating stress conditions, as well as during the interaction of the fungus with wheat roots, and during the interaction with _F. graminearum_ on wheat spikes, thus furnishing interesting novel results about the regulation of these genes and their role in the ecology of _Trichoderma_.