Since the launch of XMM-Newton in 1999 a small number of solar-like stars has been regularly monitored to follow possible long-range activity cycles; some of the stars had already been regularly monitored with the ROSAT satellite so that observations covering almost 15 years are available. I will present the available sample of X-ray stars, discuss the capabilities of XMM-Newton and Chandra to detect long term changes and present our results on cyclic variations in our sample stars. In particular, we now have an almost complete coverage of one X-ray cycle of 61 Cyg A.
