Pericardial adhesions complicate re-operative cardiac surgery and several attempts have been made to reduce adhesion formation. The efficacy of bio-absorbable oxidized regenerated cellulose in preventing post-operative pericardial adhesions was evaluated in the present study. Forty New Zealand white rabbits were divided into four groups of 10. In all rabbits an area of pericardium (2 x 2 cm) was excised. The wound was left open in groups I and 2 but replaced with bio-absorbable oxidized regenerated cellulose in groups 3 and 4. Rabbits in groups 1 and 3 were killed 3 weeks after surgery and those in groups 2 and 4 were killed at 6 weeks. Groups 1 and 2 showed more severe pericardial adhesions, more fibrous reaction and increased visibility of coronary vessels than groups 3 and 4, although there was no difference in inflammation. Light microscopy showed a mesothelium-like cell layer in groups 3 and 4. It is concluded that bio-absorbable oxidized regenerated cellulose may be suitable in patients receiving staged cardiac surgery and in those with a high probability of re-operation.