We investigated the role of interleukin 8 (IL-8) in the pathogenesis of proliferative vitreoretinopathy (PVR). The IL-8 level in the vitreous and the blood of 20 patients with PVR was measured by a specific enzyme-linked immunoassay method. Vitreous from cadaver eyes (n = 20) was used as the control. The IL-8 level in the vitreous was between 31.3 and 65 pg/ml in 40% of eyes with PVR. IL-8 was detected neither in the blood of the patients with PVR nor in the vitreous from cadaver eyes. IL-8 levels in the vitreous did not correlate with either the grade of PVR or the duration of symptoms. These results suggest that IL-8 may play a role in the pathogenesis of PVR.