Electron plasma oscillations have been observed in the solar wind upstream of the Martian bow shock by the plasma wave system (PWS) on the Phobos 2 spacecraft. These waves occurred when the interplanetary magnetic field line through the spacecraft position was connected to the shock, i.e., when the spacecraft went through the electron foreshock region in which suprathermal electrons accelerated at the bow shock were streaming back from it. The PWS observations are compared to the expectations one might have in light of the results obtained in the Earth's electron foreshock, which are briefly reviewed. The spectrum of the electron plasma oscillations peaks at or near the ambient solar wind plasma frequency. We then have an estimate of the solar wind plasma density upstream of the Martian bow shock. The 12-min averages of the plasma density are shown to vary between less than 0.5 cm-3 and 19 cm-3 from February 1 to March 26, 1989. This corresponds to an electron plasma frequency range from 6.4 to 39 kHz. Moreover, some structures were observed in the electron foreshock region of Mars. They are presented and tentatively interpreted. ¿ American Geophysical Union 1992