Upward flowing ion beams are a typical feature observed in the auroral acceleration region. Observations show that a significant part of the upward field-aligned acceleration of the ions takes place at altitudes between 5000 and 10,000 km. Another frequently observed feature in these regions are solitary waves (or weak double layers, as they are often called). These solitary structures have been observed practically only inside ion beams. In this letter we compare the occurrences of ion beams and solitary waves as a function of altitude. It is shown that there is a clear correlation between the occurrence probabilities of these two phenomena. This suggests that some of the acceleration is due to the solitary waves. Alternative interpretations are that the ion beams, accelerated by some other mechanism, are the cause of the SWs, or that these two phenomena are independent consequences of the same physical process. ¿ American Geophysical Union 1994