Argon laser iridotomy was performed on 140 eyes, with greater than one year postoperative follow-up in 88 eyes. Iris holes were satisfactorily produced in every eye treated, with two-thirds having only one treatment session. Late reclosure of laser iridotomy was rare and easily treated. At an average of 1.8 years after treatment, visual acuity was the same or improved in 85% of the eyes. Cataract progression was responsible for those eyes with decreased acuity; the rate of progression being comparable to similar groups of aged persons treated by surgical iridectomy for angle closure types of glaucoma. Other complications were temporary and did not affect vision. Laser iridotomy appears to have particular advantages in certain patients, particularly those with chronic angle closure glaucoma, aphakic pupillary block, or incomplete surgical iridectomy.