Purpose: The purpose of this study was to evaluate the presence of nitric oxide (NO) and cytokines such as interleukin 1 beta, interleukin 2 receptor (IL-2R), interleukin 6 and tumor necrosis factor a on aqueous humor after neodymium:YAG (Nd:YAG) laser posterior capsulotomy, Methods: Fifteen rabbits (30 eyes) with dense posterior capsule opacities underwent Nd:YAG capsulotomy 4 months after phacoemulsification cataract surgery. After general and topical anesthesia, Nd:YAG capsulotomy was performed using an equal number of shots and power setting on all eyes. Aqueous humor specimens were collected from each eye preoperatively and at 12, 24 and 48 h after the surgery to determine NO and cytokine levels. Results: The levels of NO and cytokines except IL-2R were significantly high as compared to preoperative levels in all eyes at 12 and 24 h postoperatively (p<0.05). Although the levels of NO and cytokines were higher than preoperative levels at 48 h, the differences were not statistically significant (p > 0.05), Conclusion: These findings suggest that NO and cytokines appear to be potential inflammatory mediators in the occurrence of early inflammation following Nd:YAG posterior capsulotomy. Copyright (C) 2000 S. Karger AG, Basel.