  Mkn 421 was observed by Chandra twice, on November 5, 1999 as part of the
Chandra calibration program, with the ACIS-HETG configuration, and on May 29,
2000 following our Target Of Opportunity request aimed to catch the source in
an ultra-high state, with both the ACIS-HETG and the HRC-LETG configurations.
In this contribution we present and compare the two Chandra-MEG observations of
Mkn 421, which lasted 26 and 19.6 ks respectively.
