The authors received the charts and photographs of 175 patients who had suspicious melanocytic lesions of the iris and who were followed without treatment. Only eight (4.6%) of these lesions showed clinical evidence of enlargement during follow-up intervals of 1 to 12 years (mean, 4.7 years). Features that were associated with enlargement of the lesion included medial location of the mass on the iris and presence of pigment dispersion onto the adjacent iris and anterior chamber angle structures. Features that were unassociated with growth of the lesion included patient age and sex, intraocular pressure, iris color, tumor size and vascularity, and presence of pupillary distortion, ectropion iridis, and sector cataract. From these results, recommendations are made which can assist the ophthalmologist in the management of pigmented iris lesions.