In order to find a difference in the biocompatibility of different IOL-materials we examined the lens-surface of poly(methylmetacrylate)-(PMMA-), heparin surface-modified PMMA-(HSM-PMMA-) and hydrogel-IOLs in a prospective study by specular microscopy. Documentation consisted of cellular reaction, precipitates on the lens-surface and irregularities of the IOL-material. Early postoperative on HSM-PMMA and hydrogel-IOLs there were fewer fibroblast-like cells as compared to PMMA-IOLs. In the later postoperative period foreign body giant cells were seen on PMMA-IOLs in 26.6%, on HSM-PMMA and hydrogel-IOLs in less than 10% of the cases. In cases with increased postoperative inflammation or contact between uveal tissue and lens-surface we found more cells and in a higher percentage. Concerning precipitates on the surface and material irregularities we also found lens-specific differences. Clinical results were satisfactory for all lens-types.