Encapsulated filtering blebs associated with elevated intraocular pressure or symptomatic dellen formation, unresponsive to conservative therapy, developed in 24 of 222 eyes following glaucoma filtering surgery over a five-year period, an incidence of 11%. Nine of 13 eyes were treated successfully with primary needling of the bleb. Ten of 11 eyes were successfully treated with primary bleb revision. Four eyes were successfully treated with a combination of needling and surgical revision and one eye required cyclocryotherapy. The overall success rate of needling or bleb revision was 96% after an average follow-up of 20 months. Thus, encapsulation of the filtering bleb, although requiring additional surgery in many cases, carries a favorable long-term prognosis.