We have observed with the BeppoSAX satellite the quiescent counterpart of the Soft Gamma-ray Repeater SGR 1806–20 .
Observations performed in October 1998 and in March 1999 showed that this pulsar continued its long term spin-down trend at an average rate of \sim 8 10 ^ { -11 } s s ^ { -1 } while its flux and spectrum remained remarkably constant between the two observations , despite the soft gamma-ray bursting activity that occurred in this period .
We also reanalyzed archival ASCA data , that when compared with the new BeppoSAX observations , show evidence for a long term variation in luminosity .