As a generalization of the zonal response coefficient first introduced by Agnew and Farrell (1978), we define the zonal response function &kgr; of the solid earth-ocean system as the ratio, in the frequency domain, of the tidal change in Earth's rotation rate to the tide-generating potential. Amplitudes and phases of &kgr; for the monthly, fortnightly, and 9-day lunar tides are estimated from 2 1/2 years of ver long baseline interferometry UT1 observations (both 5-day and daily time series), corrected for atmospheric angular momentum effects using NMC wind and pressure series. Using the dynamic ocean tide model of Dickman (1988a, 1989a), we also predict amplitudes and phases of &kgr; for an elastic earth-ocean system. The predictions confirm earlier results which found that dynamic effects of the longer-period ocean tides reduce the amplitude of &kgr; by about 1%. However, agreement with the observed &kgr; is best achieved for all three tides if the predicted tide amplitudes are combined with the much larger satellite-observed ocean tide phases; in these cases the dynamic tidal effects reduce &kgr; by up to 8%. Finally, comparison between the observed and predicted amplitudes of &kgr; implies that anelastic effects on Earth's rotation at periods less than fortnightly cannot exceed 2%. ¿ American Geophysical Union 1990