Background: The Wuerzburg bleb classification score (WBCS) aims at an objective and standardized assessment of the developing filtering bleb after trabeculectomy, in order to detect and treat bleb scarring at the earliest possible stage of development. The purpose of this retrospective study was to evaluate the prognostic value of the early postoperative WBCS for the long-term outcome of trabeculectomy. Methods: The WBCS is a grading system for clinical bleb morphology. It evaluates the following parameters: vascularization, corkscrew vessels, encapsulation and microcysts. The WBCS of 113 eyes of 113 consecutive patients after trabeculectomy was determined 1 day, 1 and 2 weeks, 3, 6 and 12 months after surgery. Complete success was defined as an intra-ocular pressure (IOP) <21 mm Hg and >20% pressure reduction without glaucoma medication after 1 year. Results: A complete success rate of 73.9% and a qualified success rate of 82.4% were achieved 1 year after surgery. The average total bleb score during follow-up in the success group was always higher than in the failure group, but there was no statistically significant difference at any time. The bleb average score for eyes with an IOP of ≤12 mm Hg after 2 weeks was significantly higher (p = 0.005) than for eyes with an IOP ≧13 mm Hg at the end of follow-up. Conclusion: Patients with a higher early WBCS postoperatively had a significantly lower IOP 1 year after surgery. However, the study could not reveal a certain prognostic value of the early total bleb score using the WBCS for the long-term complete success of trabeculectomy.