Published claims that the reflectivity of the western boundary of the equatorial Pacific is near 100% are examined by using TOPEX/Poseidon data from October 1992 to February 2000. We perform a Fourier analysis of sea surface height measurements and define the variability consistent with the Rossby wave and Kelvin wave dispersion relationship as the energy of Rossby wave and Kelvin wave, respectively. Basin-scale Rossby waves dominate in the period ranges of 180--250 and 270--450 days. Their largest amplitudes are at 4¿ and 6¿N, respectively. Kelvin waves dominate in distinguishable period ranges of 67--76 and 106--170 days. Because the wavelengths of the Kelvin waves generated from the reflection of low-frequency Rossby waves are much longer than the width of the basin, they cannot be readily differentiated from large-scale forced motions. An upper bound on the reflection coefficient of the Rossby wave is thus estimated as 31% for Rossby waves with periods of 180--250 days. The duration of TOPEX/Poseidon data is too short for studying the reflectivity of the lower-frequency Rossby waves.