A new species, Trichoderma stromaticum, was isolated from ‘witches' broom’ of cacao (Theobroma cacao) in Brazil caused by Crinipellis perniciosa. The Trichoderma was reported earlier as T. viride and T. polysporum. Trichoderma stromaticum reduced new inoculum through the suppression of basidioma formation. It is characterised by having conidia that slowly become yellow-green in agar culture and by stout, ‘Pachybasium-like’, phialides formed on the surface of stromatic structures. The closest relations of T. stromaticum are T. harzianum and T. virens.