  The XMM-Newton data presented here are the first X-ray observation of the
Seyfert 2 galaxy NGC4138. Although the galaxy has been pointed by ROSAT-HRI, it
was not detected, with a flux upper limit of about 1.1x10^-13 erg cm^-2 s^-1 in
the 0.2-2.4 keV energy band. XMM-Newton performed the observation on 26
November 2001. The source is detected for the first time in X-rays with
F[0.2-2.4]=1.0x10^-13 erg cm^-2 s^-1, in agreement with the upper limit of
ROSAT. The source spectrum is typical of Seyfert 2 galaxies. We find heavy
obscuration (N_H about 8x10^22 cm^-2) and a flat photon index (1.6). The source
intrinsic luminosity is about 5x10^41 erg/s in the 0.5-10 keV energy band.
