Daunorubicin (DNR), an antibiotic-antimetabolite, was used as an adjunct to standardized partialthickness filtration surgery in 21 rabbits to determine its effects on that surgery. Postoperatively, one of the eyes of each rabbit received subconjunctival injections of DNR 25 µg or 50 µg, while the fellow eyes received only diluent, daily for 2 to 14 days. Bleb survival, fistula patency, the thickness of the subconjunctival connective tissue, and postoperative complications were investigated. The filtration blebs lasted significantly longer (P < .005), the rate of fistula closure was significantly lower (P < .005), and the subepithelial connective tissue was much looser and thicker in the experimental eyes than in the control eyes. Corneal toxicity occurred more frequently in the eyes treated with the higher-dose DNR than in those treated with the lower dose and in the control eyes.