We study the influences of El Ni¿o phenomena on correlations between short-period variations of atmospheric and geodetic excitation functions of polar motion during 1980--1998. The correlation between these two excitation functions varies with time, with correlation coefficients computed for 1 year spans reaching maxima of 0.7--0.8. Series of these correlation coefficients themselves correlate with El Ni¿o and Southern Oscillation Index (SOI) data, indicating the influence of El Ni¿o and SOI on atmospheric and geodetic excitation functions of polar motion and on polar motion itself. The maximum correlation coefficients for Ni¿o 4 sea surface temperature data is equal to 0.8 in the case of El Ni¿o events in 1983 and 1987. Impacts of El Ni¿o on polar motion have an impulsive character causing irregular variations of polar motion during the El Ni¿o epochs. ¿ 2000 American Geophysical Union