Posterior lip sclerectomies were performed in rabbits and cytosine arabinoside (Ara-C) was applied by topical instillation or subconjunctival injection. In both groups, the mean intraocular pressure (IOP) of the treated eyes was significantly lowered at postoperative week 1 and 2, but there was no significant difference between the mean IOP of the control eyes and that of the treated eyes at postoperative week 3 and 4. In both groups, at postoperative week 2, the sclerectomy sites of the control eyes were totally occluded by granulation tissue, but those of the treated eyes were partially replaced by granulation tissue. At postoperative week 4, the sclerectomy sites of the treated eyes were totally occluded by the granulation tissue ultimately in both groups. There were no differences in the mean IOP and the histologic finding of the treated eyes between the topical instillation group and the subconjunctival injection group. We concluded that either topical instillation or subconjunctival injection of Ara-C can delay wound healing at the surgical site after glaucoma filtering surgery in rabbits.