Aim: Previous studies have shown that radiotherapy is a stimulus for cyclooxygenase-2 (COX-2) expression and that use of COX-2 inhibitors enhances the radio sensitivity of tumor cells. The objective of this study was to evaluate COX-2 expression, and its correlation with tumor regrowth after irradiation, in enucleated eyes with uveal melanomas.Methods: Fifteen tissue samples from patients who underwent enucleation after radiotherapy between 1988 and 2001 were used. Nine cases (60%) were enucleated because of tumor regrowth and six (40%) because of severe complications of radiotherapy. Specimens were immunostained for COX-2, and tumor cells were evaluated for specific cytoplasmic and granular immunostaining. COX-2 expression for these cases was compared with that in the previous study including 40 non-irradiated uveal melanoma cases. COX-2 expression was also correlated with tumor regrowth after radiotherapy.Results: Two cases (13.3%) were positive and thirteen (86.7%) were negative for COX-2 expression. One of the positive cases had been enucleated because of tumor regrowth and one because of radiotherapy complications. There was no relationship between tumor regrowth and COX-2 expression. COX-2 expression was significantly lower in irradiated cases than in non-irradiated cases in the previous study (p