ABSTRACT Trichoderma species have been identified as potential biocontrol agents of many plant pathogenic fungi, including Botrytis cinerea Pers., one of the major pathogens in tomato (Solanum lycopersicum L.) production in the Republic of Macedonia. The aim of this study was to evaluate the in vitro antagonistic activity of Trichoderma asperellum and T. harzianum against 18 genetically diverse B. cinerea isolates. The results showed considerable antagonistic abilities of both Trichoderma species against all tested B. cinerea isolates. Both antagonists significantly (p < 0.01) inhibited the mycelial growth (T. asperellum from 74.246% to 96.915% and T. harzianum from 71.072% to 95.889%) and conidial germination (T. asperellum from 76.932% to 95.107% and T. harzianum from 76.933% to 93.658%) of B. cinerea isolates. The antagonistic abilities were not related to the genetic group, but apparent association with the region of origin of the pathogen isolates was observed. Trichoderma asperellum and T. harzianum are promising biocontrol agents for control of gray mold disease in tomato.