The subject is to compare the middle term efficiency of surgical peripheral iridotomy and Argon laser iridotomy for primary closed angle glaucoma. We have considered reopened angles on 360 degrees after a crisis of closed angle; eyes with a positive "neosynephrine - pilocarpine" test; the second eye of a primary closed angle glaucoma and primary mixed glaucoma. Sixty affected eyes have been divided in two groups in a randomized study. Group A: Thirty eyes requiring a bilateral surgical peripheral iridectomy, Group B: Thirty eyes requiring a bilateral Argon laser iridotomy. The patients are regularly followed at intervals of: one week, three months, six months, one year and two years. Four parameters have been researched: 1. Intraocular pressure between 9 h-12 h a.m. Intraocular pressures lower or equal to 22 mmHg were considered to be successes. 2. Far visual acuity with correct lenses. 3. Opacity of the crystalline lenses: normal or sclerosed (0, +/-, +) cataract (++, ). 4. Post-operative complications. Some cases have required several periods of Argon laser photocoagulation (colorless iris, older patients) but we prefer a proper result immediately in order not to take any risks with pupillary blocking-up. The statistical analysis gives the following results: Same tonometric results according to the different technics even if the treatment has been prophylactic (positive provocation test; second eye) or curative (primary closed-angle glaucoma with solvable crisis; mixed glaucoma). No significant difference of visual acuity between the two groups after two years. Similarly, we have not found a significant difference between both techniques in each considered age group two years after the operation.(ABSTRACT TRUNCATED AT 250 WORDS)