Magnetic field and medium energy particle data acquired with the AMPTE/CCE spacecraft have been used to study substorm-associated ULF pulsations occurring in the midnight sector at a radial distance of 8 to 9 RE. The particle data are used not only to identify ion injections but also to detect the electric field of ULF waves. A case study of events observed on 23 May 1985 (day 143) shows that the waves have the properties of a fundamental-mode standing Alfv¿n wave. The waves started nearly simultaneously with the Pi 2 pulsations observed at the Syowa station (L=6.1) near midnight local time. However, different frequencies are observed on the ground and in space, which is consistent with the view that the Alfv¿n waves are excited at the local Alfv¿n resonance frequency. This CCE observation gives the first unambiguous evidence of substorm-associated standing Alv¿n waves in the nightside magnetosphere. ¿ American Geophysical Union 1988