To determine indocyanine green (ICG) angiographic features and evaluate the extent of choroidal involvement in proven cases of posterior ocular sarcoidosis. Nonrandomized controlled trial. Nineteen patients (14 females, 5 males; average age, 56 +/- 4 years) with clinically typical posterior sarcoidosis (biopsy-proven in 6 cases and fulfilling the other diagnostic criteria in 13 cases) participated, with 10 control subjects (average age, 48 +/- 7 years). Criteria for the diagnosis of sarcoidosis were a positive biopsy result or the presence of at least three of the following four criteria: elevated serum angiotensin-converting enzyme, elevated lysozyme, cutaneous anergy, and hilar lymph node enlargement. Indocyanine green angiography was performed according to a standard angiographic protocol used in inflammatory disorders. Indocyanine green angiographic features and proportion of choroidal inflammatory involvement were measured. Indocyanine green angiographic features could be classified into four main patterns. The first pattern is hypofluorescent choroidal lesions in the early and intermediate phases, irregularly distributed, invisible on funduscopy or fluorescein angiography, and localized in the midperiphery (63% of patients), in the macula (11%) or in both regions (26%) with an average dot diameter of 0.31 +/- 0.03 disc diameters. These lesions either became isofluorescent in the late phase of the angiogram (Type 1, present in all patients) or remained hypofluorescent (Type 2, present in 84% of patients). The second pattern is focal hyperfluorescent pinpoints visible in the intermediate and late phases (in 89% of patients). The third pattern is fuzzy choroidal vessels with leakage in the intermediate phase of the angiogram, and the fourth pattern is diffuse late zonal choroidal hyperfluorescence with staining in the late phase of the angiogram, both features being present in all patients. Indocyanine green angiography allowed the authors to assess and quantify the hitherto unknown extent of choroidal involvement in ocular sarcoidosis. Furthermore, characteristic ICG findings might represent an additional valuable tool for diagnosing and monitoring this disease.