The passive laser satellite GFZ-1 (215 mm diameter, 21 kg mass, 60 retroreflectors) is orbiting the Earth since April 1995. GFZ-1 was placed in a circular, medium-inclination orbit with an initial altitude of 390 km, the lowest ever flown for a geodetic satellite. GFZ-1 is tracked with cm-accuracy during its expected lifetime of 4 years by some 15 ground stations of the international laser ranging net. The scientific objective of this small satellite mission is the improvement of the current knowledge of the Earth's gravity field by exploiting observed gravitational orbit perturbations, taking advantage of the increased sensitivity due to the very low orbit. A first tentative laser data evaluation resulted in a pronounced contribution of GFZ-1 data to the spectral terms around orders 31 and 46 of the spherical harmonic expansion of the geopotential when solved in combination with satellite tracking data from 34 other satellites, leading to small but perceptible improvements in the global geoid and gravity field model. ¿ American Geophysical Union 1996