The influence of corona emission during and immediately after a lightning flash is studied experimentally as well as by numerical modeling. Simultaneous electric field measurements made at ground level, 30 m above ground level, and over water (zero level) show that corona ions generated during the flash can strongly modify not only the field recovery that follows, but also the brief field signature during the flash. The higher the field intensity reached during the flash, the stronger this influence. As a matter of fact, under strong field conditions, the initial recovery rate appears to be higher at ground level than aloft, and the overall surface field change produced by a lightning flash can be considerably reduced owing to the creation of ions. A numerical model computes the modification, by this phenomenon, of the field evolution at various levels. ¿ American Geophysical Union 1989