Deep-seated infections due to Trichosporon species are emerging mycoses that have a very poor prognosis in patients with persistent neutropenia. This study elucidated the mycological characteristics of Trichosporon strains obtained from deep-seated infections in Turkish patients and identified by DNA sequence analysis of intergenic spacer (IGS) region 1 of the rDNA locus. In addition, we genotyped the major causative agent, T asahii, and evaluated the in vitro drug susceptibility of the isolates. While 87 (81.3%) of the 107 isolates were T asahii, the remaining 20 were T. faecale (14.0%), T asteroids (0.9%), T. coremiiforme (0.9%), T japonicum, (0.9%), T. lactis (0.9%), and a new species (0.9%). In addition to the eight known T. asahii genotypes, one novel genotype was identified. The distribution of the T. asahii genotypes in this study were genotype 1 (79.3%), followed by 5 (8.0%), 3 (6.9%), 6 (3.4%), 4 (1.1%), and 9 (1.1%). Turkish isolates showed low susceptibility to amphotericin 13, 5-flucytosine, and fluconazole. Although relatively low minimum inhibitory concentrations (MICs) were found with all drugs, voriconazole appeared to be the most active. The MICs of the non-Trichosporon asahiiTrichosporon species were similar to those of the T. asahii strains. Our findings suggest that Trichosporon species isolated from Turkish patients are more diverse than those reported from other countries.