  We present a first study of truncation of the stellar disks of spiral
galaxies in the near infrared. Observations of NGC4013, NGC4217, NGC6504 and
NGC5981 were made with the CAIN NIR camera on the CST in Tenerife. This
wavelength range provides the best description of the phenomenon, not only
because extinction effects are minimized, but also because the distribution of
the old stellar population is directly obtained. The four galaxies are edge-on
and an inversion method was developed to obtain the deprojected profiles. We
did not assume any model of the different galactic components. The ``truncation
curve'', i.e. T(R)= mu(R)- mu_{D}(R), where mu is the actual surface brightness
in mag/arcsec^2 and mu_{D} the exponential disk surface brightness, has been
obtained with unprecedented precision. It is suggested that T(R) is
proportional to (R_{t}-R)^{-1}, where R_{t} is the truncation radius, i.e. the
radius beyond which no star is observed.
