Glaucoma surgery has evolved over the past 30 years from the full-thickness procedure to the guarded filtration procedure. However, many of the risks and complications attendant with the full-thickness procedure, including endophthalmitis, hypotony, cataract progression, and filtration failure, continue to plague the glaucoma surgeon performing the guarded filtration procedure, although at lower incidences. With proper modification of technique, such as with postoperative bleb titration and use of adjunctive antifibrotic therapy based on prognosticators for failure, the success rates of trabeculectomy reoperations can approach those of primary trabeculectomy. Such risk factors for failure include African-American race, higher preoperative intraocular pressures, previously failed filters, younger age, and uveitic and neovascular glaucomas. In this paper, we review a number of studies that analyze the risks, complications, and long-term results of glaucoma filtration surgery and discuss different surgical recommendations based on risk factors for failure as well as for performing concomitant cataract and glaucoma surgery.