Among the Arg-Gly-Asp (RGD)-containing sequences that are known to be cell-binding domains of fibronectin, 500 µg/ml of Arg-Gly-Asp-Ser (RGDS) and Gly-Arg-Gly-Asp-Ser showed 100% inhibition of the attachment of cultured lens epithelial cells (TOTL-86 cells), when they were added to culture medium and coincubated with the cells for 24 h whereas RGD at concentrations of 500, 1,000 and 2,000 µg/ml had no such activity. After 48 h of cocultivation of 800, 400 or 200 µg/ml of RGDS with TOTL-86 cells, the percentage of floating cells was 100, 30.1 or 11.1%, respectively. After 144 h of cocultivation with RGDS, the percentage of floating cells was 1.6,2.4 or 1.9%, respectively, indicating that RGDS was not cytotoxic to lens epithelial cells. However, replacing the medium with fresh medium containing new RGDS peptide resulted in floating of cells. We also studied the inhibitory effect of two other amino acid sequences that are found in cell-binding sites of the fibronectin molecule: Glu-Ile-Leu-Asp-Val-Pro-Ser-Thr (EILDVPST) and Arg-Glu-Asp-Val (REDV). At 500 and 1,000 µg/ml, respectively, neither EILDVPST nor REDV has an inhibitory effect on the attachment of TOTL-86 cells, while RGDS at a concentration of 500 µg/ml completely inhibited the attachment of the cells in 24 h of incubation.