Suturing of traumatic or surgical iris wounds has proved to be a safe and feasible microsurgical procedure. Various suture materials have been tried experimentally and clinically. If the human iris forms scar tissue the ideal suture would be an absorbable, inert, proteinfree material causing no uveal reaction. It was the purpose of this study to evaluate the ocular tissue reaction to nylon, virgin-silk and polyglycolic acid (Dexon) after suturing of an experimental iridomy in 24 rabbit eyes. The tissue response was studied by biomicroscopy, iris fluorescein colour angiography, and histology. Nylon did not disintegrate and caused virtually no inflammatory reaction. Silk showed fragmentation and complete absorption after four to six months with moderate tissue response. Polyglycolic acid gave rise to a marked uveal reaction and depolymerised from the fifth to the sixth week. There was no wound dehiscence of the iris scar and the pupillary function remained intact. It is concluded that the non-absorbable materials are superior to the currently available absorbable sutures in iris surgery.