Gas argon laser peripheral iridectomy was attempted as an alternative to surgical peripheral iridectomy in the treatment of acute angle-closure glaucoma and the prophylactic treatment of fellow eyes. Success was achieved in eyes with a blue iris if sufficient energy was given to achieve a permanent red reflex. Reasons for failure in eyes with a heavily pigmented iris are discussed. The procedure must be greatly improved before surgical peripheral iridectomy is superseded as the treatment of choice.