Ovalbumin was modified to various degrees by acylation of lysine e-amino groups with stearyl residues. Adsorption isotherms of the modified ovalbumin on hydrophobic silica were obtained. It was found that increase in degree of modification resulted in increased amounts of adsorbed protein. At high modification degree (>40%), practically identical isotherms were obtained. The adsorption data were analyzed by using the Langmuir equation, and it appeared that increase in modification led to decrease in area per adsorbed protein molecule, while the adsorption constant remained unchanged.