The exciton equilibration in the light-harvesting complex of photosystem 2 at room temperature was studied with pump-probe experiments under quasi-stationary conditions. The measurements were performed with two dye lasers, which had a pulse diuation of 10 ns and a spectral bandwidth of less than 0.01 nm. The relative probe beam transmission ffom 640-690 nm was recorded at different excitation wavelengths, varied from 645 to 685 nm. Two maxima were observed at 650 nm (Chl b absorption region) and at 680 nm (Chl a absorption region). The relative probe beam transmission in the Chl a region showed a course nearly independent of the pump beam wavelengťh in contrast to a weak dependence in the Chl b region. Measurements of the relative probe beam transmission as a function of pump beam intensity revealed a dominating exciton-exciton annihilation in the Chl a absorption region. In the Chl b region exciton-exciton annihilation was only marginal.