AbstractSamples of the vitreous were analysed in order to identify changes of soluble proteins in vitreo‐retinal disease. The soluble proteins of the vitreous were separated on an anion exchange column (Mono‐Q). The degree of neutral proteolytic activity in vitreous body was also measured. The vitrous from cataract cases without vitreoretinal disease was characterized by its low content of soluble proteins equivalent to about 1% of that of serum. Albumin and transferrin were the major identified components and their concentrations were approximately 0.85 and 0.03 g/l, respectively. In cases with vitreoretinal disease the vitrous showed changes of total soluble protein and the appearance of additional protein peaks. In patients with PVR the albumin concentration in the vitreous was found to be three times higher as compared to the control group consisting of patients with cataract. Neutral proteolytic activity in the vitreous was relatively low in both normal and pathological vitre