Canavan, an autosomal-recessive neurodegenerative disease, is caused by a deficiency of aspartoacylase. Most children are reported to have the infantile form, becoming symptomatic between 3 and 6 months of age, after an unremarkable prenatal and perinatal course. Congenital and juvenile onset forms, although uncommon, do occur. We collected clinical information from the parents of 60 children diagnosed with Canavan disease and reviewed the literature. We conclude that Canavan disease is prenatal in onset with variability in progression. The variable clinical course cannot be explained by genetic heterogeneity but probably depends on environmental factors and/or modifying genes.