During recent years, solar seismology comes into a new era due to the quantity andthe quality of data. In particular, data sets spanning asolar cycle or an important fraction of this cycle become available, allowing aseismic investigation of this magnetic cycle. However, despite some interestingresults, this investigation has to face seriouslimitations. On the other hand, some new analysis techniques in helioseismologyprovides unexpected and spectacular results on magnetic regions, maybe openinga new way to the understanding of the magnetic cycle.