A consecutive series of 71 cases of late onset endophthalmitis (defined as onset of symptoms at least 2 weeks after surgery) were reviewed to determine the association of this entity with glaucoma surgery filtering blebs and to identify any predisposing factors. Sixteen cases were associated with filtering blebs and two with inadvertent blebs following cataract surgery. Onset of endophthalmitis ranged from 24 days to 20 years after surgery (mean, 6.9 years). Possible contributing factors included trauma, vitreous wicks, and bleb leak. Twelve cases were culture-positive, with 5 cases of Staphylococcus epidermidis; 2, Staphylococcus aureus; 4, Streptococcus; and 1, Pseudomonas. There were no cases of Hemophilus. The more virulent organisms were generally associated with a poor visual outcome. The organisms recovered in this series were similar to those found in postoperative endophthalmitis not associated with filtering blebs.