The early last glacial termination was characterized by intense North Atlantic cooling and weak overturning circulation. This interval between similar to 18,000 and 14,600 years ago, known as Heinrich Stadial 1, was accompanied by a disruption of global climate and has been suggested as a key factor for the termination. However, the response of interannual climate variability in the tropical Pacific (El Nino-Southern Oscillation) to Heinrich Stadial 1 is poorly understood. Here we use Sr/Ca in a fossil Tahiti coral to reconstruct tropical South Pacific sea surface temperature around 15,000 years ago at monthly resolution. Unlike today, interannual South Pacific sea surface temperature variability at typical El Nino-Southern Oscillation periods was pronounced at Tahiti. Our results indicate that the El Nino-Southern Oscillation was active during Heinrich Stadial 1, consistent with climate model simulations of enhanced El Nino-Southern Oscillation variability at that time. Furthermore, a greater El Nino-Southern Oscillation influence in the South Pacific during Heinrich Stadial 1 is suggested, resulting from a southward expansion or shift of El Nino-Southern Oscillation sea surface temperature anomalies.