This paper presents the results of an ionospheric tomography experiment over midlatitude Europe. The campaign yielded 539 reconstructions over a 45-day period in spring 1995. Special attention is paid to the performance of the reconstruction algorithm, specifically by comparison with ionosonde data. Tomography and soundings tend to agree on electron density, but they do not agree on the height of maximum electron density: tomography seems to overestimate Hmax. Whereas tomography finds a daily oscillation in Hmax between 250 km (daytime) and 450 km (nighttime), the soundings indicate an oscillation between 200 and 250 km. ¿ 1998 American Geophysical Union