We present results from a monitoring campaign on Cyg X-1 during a large X-ray flare. During this period, the spectrum of the source evolved significantly: the higher the soft flux the steeper the spectrum. The evolution follows a simple pattern of pivoting around 8–10 keV, which is similar to that observed in the 1996 state transition. The power density spectrum during the flare is typical of the source during a spectral state transition, so do the correlations among temporal properties and the spectral properties. Therefore, an X-ray flare and a spectral state transition appear to be similar phenomenon and the difference seems to be only quantitative. ©2001 American Institute of Physics.