Argon laser trabeculoplasty (ALT) has been successful in controlling open-angle glaucoma, but a significant number of patients still require filtration surgery. Concern that post-laser inflammatory changes or alterations of structural anatomy with damage to the trabecular meshwork may adversely affect the outcome of filtration surgery prompted a retrospective review of 87 consecutive eyes with open-angle glaucoma that required filtration surgery following failed ALT. The follow-up period was at least 6 months, with a mean of 18 months (6 to 38 months). Posterior lip sclerectomy was chosen for 69 eyes and trabeculectomy for 18 eyes. The overall success rate of filtration surgery during the follow-up period was 92%. There was no recognized difference in the response to filtration surgery following ALT.