Alagille syndrome is an autosomal dominant disorder caused by mutations in the JAG1 gene. The JAG1 gene encodes a ligand for the Notch receptor and thus is part of a critical signaling pathway during development. The ophthalmologist can play an important role in the diagnosis of Alagille syndrome by identifying the characteristic ocular findings. These include a posterior embryotoxon, optic disc drusen, angulated retinal vessels, and a pigmentary retinopathy. Despite recent advances in the genetics of Alagille syndrome, the correlations between genotypes and phenotypes remain incompletely defined.