OBJECTIVE: To report indocyanine green (ICG) angiography anomalies in ocular syphilis. DESIGN: A noncomparative, interventional case series. PARTICIPANTS: Eight patients (16 eyes) affected by ocular syphilis. METHODS: All patients presenting with a diagnosis of active ocular syphilis between January 1994 and December 2001 were evaluated by a standard fluorescein and ICG angiography protocol. ICG angiography was repeated after completion of systemic antitreponemal and antiinflammatory treatment. RESULTS: ICG angiography anomalies were detected in 12 (75%) of 16 eyes. Two types of anomalies were observed: late-phase scattered hyperfluorescent spots (11 eyes) and persistent staining of retinal vessels (1 eye). Of these 12 eyes, 4 had no alteration by concomitant fluorescein angiography. When ICG angiography was repeated (5 +/- 1 weeks after the beginning of treatment), ICG angiography anomalies disappeared. CONCLUSIONS: ICG angiography may be a valuable tool in the assessment of patients with active ocular syphilis. Retinal and choroidal vascular anomalies can be determined that would otherwise go undetected by funduscopy and/or fluorescein angiography. It can also be useful in monitoring antitreponemal therapy.