Purpose: To report the outcome of 5-fluorouracil (5-FU)-augmented bleb needling revision of failed and failing filtration blebs and to identify risk factors for failure, indicators for success, and any complications of the procedure. Design: Prospective, observational, noncomparative, interventional case series with survival analysis. Methods: The results of 101 bleb needling procedures augmented with subconjunctival 5-FU injection were determined after a minimum follow-up of 9 months. Kaplan-Meier plots were constructed and a Cox proportional hazards regression analysis was performed to assess the association between study factors and time to failure. Main Outcome Measures. Reduction in intraocular pressure (IOP) by 2 criteria (<22 mmHg, >30%), glaucoma medications, complications, and factors associated with outcome. Results: At the time of their last follow-up visit, 60 eyes had an IOP <22 mmHg, mean IOP being reduced from 26.5 mmHg to 18 mmHg after a median of 1 needling procedure (mean, 1.6). The median interval between the "index" filtration surgery and the first (or only) needling procedure was 3.1 months, with a range of 10 days to 11 years. There was a reduction in mean number of topical antiglaucoma agents from 0.7 to 0.2 per successful eye and a median follow-up duration of 18.7 months (range, 9.3-52.0 months). Thus, the overall cross-sectional success rate of the procedure at the time of the last visit was 59.4%. Strong evidence was found for an association between the immediate attainment of a low IOP (<11 mmHg) and longer survival times. None of the other proposed factors that may have affected outcome were identified as having a statistically significant effect; however, this may have been the result of the low statistical power for some of the factors in this study. Conclusions: These data suggest that bleb needling augmented with 5-FU is a safe and effective method by which a significant number of failed or failing filtration blebs can be rescued from failure. Attaining an immediate reduction in IOP to <11 mmHg seems to be a favorable factor with respect to reasonably long-term efficacy. (C) 2004 by the American Academy of Ophthalmology.