A slab optical waveguide(SOWG) has been used to study the initial adsorption process of hemoglobin on glass surface using time-resolved absorption measurement of the evanescent wave. Absorbance data were taken at 50-ms time interval during the first 12 s after the measurement has started. Results showed that hemoglobin was adsorbed on glass and the data demonstrated excellent agreement with Langmuir-like model.