Background: Subretinal or intraretinal hemorrhage may occur after photodynamic therapy (PDT). However, risk factors for post-PDT hemorrhage have not yet been investigated. Methods: We reviewed the medical records of patients who had undergone PDT for subfoveal choroidal neovascularization secondary to age-related macular degeneration. Primary outcomes were the occurrences of hemorrhages at 2 and 12 weeks after PDT. To identify the risk factors of hemorrhages after treatment, ocular and systemic factors were investigated. The secondary outcome was visual acuity. Results: Ninety-two eyes from 92 patients were analyzed. New hemorrhages developed in 9 (9.8%) within 2 weeks and in 8 (8.3%) between 2 and 12 weeks after PDT. Hypertension [ odds ratio (OR) 356.9, 95% confidence interval (CI) 3.7-34,487.1], minimally classic lesion (OR 53.4, 95% CI 2-1,429) and advanced age (OR 1.2, 95% CI 1-1.5) were related to hemorrhagic events within 2 weeks after PDT. A tendency toward recurrent hemorrhage was noted after repeat treatments (p < 0.05). Forty-four percent of the patients with a hemorrhagic event within 2 weeks after PDT experienced decreased vision. Conclusion: Hypertension, minimally classic lesion, advanced age and a previous hemorrhagic event were associated with the development of hemorrhage within 2 weeks after PDT. Copyright (C) 2008 S. Karger AG, Basel