The authors evaluate the finding on the corneal endothelium before and after operation of cataract. For examination of the endothelium they used a specular microscope SP 1.000 of Topcon Co. The group comprised 64 eyes of 64 patients. The patients were divided at random into two groups. The first group comprised 26 patients, where ECCE was performed. The second group comprised 38 patients and the opaque lens was removed by phacoemulsification. The mean age in the first group was 69.3 years and in the second group 70.7 years. The same viscoelastic material (methylcellulose) was used and the same synthetic lens from PMMA material was implanted into the capsule. The endothelium was examined one day after operation and on the 7th to 10th day after operation. The following parameters were evaluated: density of the endothelial cells in the centre, mean cell size, polymegethism, coefficient of variation, pleomorphism. In the group of patients who had ECCE the loss of endothelial cells was 18.53%, in the group with phacoemulsification of the nucleus the loss was 16.43%. This difference is not statistically significant. After operation in both groups enlargement of the minimal, maximal as well as mean cell size was observed, the coefficient of variation increased while the grade of cell hexagonality decreased. However these differences in endothelial cells were not statistically significant. After operation of cataract not only endothelial cells are lost but also significant changes in cell morphology occur.