A number of Kirramyces J. Walker et al. species, formerly accommodated in the genus Phaeoseptoria Speg., are pathogens of Eucalyptus L’Hérit. spp. A new species, K. destructans M.J. Wingf. & Crous sp. nov., associated with a leaf blight disease in Northern Sumatra, Indonesia, is described. This disease is most common on leaves of E. grandis Hill: Maid., but has also been observed on other Eucalyptus spp.