AIM: To evaluate whether aqueous humor levels of pigment epithelium-derived factor (PEDF) are increased in patients with uveitis METHODS: Aqueous humor levels of PEDF and tumour necrosis factor alpha (TNFalpha) were determined by ELISA in 34 uveitis samples and 9 cataract control samples. RESULTS: Aqueous humor PEDF and TNFalpha levels were significantly higher in patients with uveitis than in controls (mean (SD) 6.4 (0.8) v 1.3 (0.2) microg/ml and 14.7 (3.8) v 4.2 (0.4) pg/ml, respectively; p<0.01). A positive correlation between PEDF and TNFalpha was found in patients with uveitis (r = 0.40, p<0.01). Furthermore, PEDF levels in aqueous humor were increased in proportion to the disease activity of uveitis. CONCLUSION: The results show that aqueous humor levels of PEDF are increased in patients with uveitis. Our observations suggest that aqueous humor levels of PEDF may be increased as a countersystem against inflammation in uveitis.