The relationship between solar wind properties and the influx of energy into the nightside auroral region, as indicated by the intensity of auroral kilometric radiation, is investigated. Fluctuations, as large as three orders of magnitude and with periods related to the solar rotation period, are found in the observed intensity of auroral kilometric radiation. Correlations are made with solar wind ion density, bulk flow speed (Vsw), total IMF strength (Bsw), ‖Vsw x Bsw‖ electric field, solar wind VswBs (where Bs is the southward component of the IMF Bz) solar wind Vsw2Bsw and VswBsw2, and the substorm parameter &egr;( = VswBsw2sin4(ϑ/2)L02). The best correlation is between the solar wind flow speed and the intensity of auroral kilometric radiation. For the 203 daily averages examined, a linear correlation coefficient of 0.78 is found.