A histologically proved nonpigmented iris cyst was seen spontaneously in a 22-year-old woman and was removed 14 years later because it enlarged and compromised her vision. The controversy involving the cause and tissue origin of these cysts is discussed. The late age of manifestation together with the histologic characteristics of this cyst favor a "spontaneous" cause arising from tissue of neuroectodermal origin, eg, the nonpigmented ciliary epithelium. The nonpigmented ciliary epithelium. The clinical characteristics of this disorder and means of treatment are reviewed.