A review of 87 cases of microbial keratitis in South Australia was made to determine the factors which influence the outcome of the disease. The preceding pathology and the extent of ulceration at presentation were found to be significant, while the presence of hypopyon was less important. Infection with Pseudomonas aeruginosa was most likely to result in a poor outcome. Most patients had a history of traumatic injury, herpes simplex keratitis, or a corneal graft. The choice of gentamicin and a cephalosporin as appropriate initial therapy in Australia was supported. The results are discussed with reference to current research objectives.